Side Dishes
This one-pan baked cod with potatoes and onions delivers bistro-quality dinner with minimal effort—juicy cod fillets, crispy golden potatoes, and caramelized onions all baked together in a single dish.
The secret lies in balancing flavors through a simple herb-infused olive oil and white wine base that keeps the fish tender while enhancing the natural sweetness of the vegetables.
What makes this recipe stand out is its foolproof technique that ensures perfectly cooked fish without drying it out. The potatoes and onions roast until tender and slightly crispy, absorbing the aromatic flavors from the cod's marinade.
With just 30 minutes of active prep and 45 minutes in the oven, you'll have a restaurant-worthy meal without the fuss.
The result is a harmonious plate where flaky cod meets creamy potatoes and sweet, caramelized onions—each bite offering a perfect balance of textures and flavors. The dish is elegant enough for company but simple enough for a weeknight, making it a go-to recipe for any occasion.
Serve with a fresh green salad or steamed vegetables to complete the meal. Here's everything you need to bring this bistro-style dinner to your table with professional results every time.
Ingredients for baked cod with potatoes and onions
Bistro-quality dinner starts with these fresh, quality ingredients baked together in one pan.
| Ingredient | Amount | Notes |
|---|---|---|
| Cod Fillets 🐟 | 2 whole | Skin-on, 6-8 oz each |
| Russet Potatoes 🥔 | 1 ½ lb | Cut into 1-inch chunks |
| Yellow Onions 🧅 | 2 whole | Thinly sliced into rings |
| Extra-Virgin Olive Oil 🫒 | ¼ cup | High-quality, fruity variety |
| Dry White Wine 🍷 | ½ cup | Sauvignon Blanc preferred |
| Fresh Dill 🌿 | ¼ cup | Chopped, stems removed |
| Fresh Parsley 🌿 | ¼ cup | Chopped, for garnish |
| Garlic Cloves 🧄 | 4 cloves | Minced, for marinade |
| Lemon Juice 🍋 | 2 tbsp | Freshly squeezed |
| Diamond Crystal Kosher Salt 🧂 | 1 ½ tsp | For seasoning and marinade |
| Freshly Ground Black Pepper 🌶️ | ½ tsp | Coarsely ground |
| Unsalted Butter 🧈 | 2 tbsp | Cold, for finishing |
The cod fillets are the foundation—opt for skin-on cuts from a trusted seafood purveyor like Whole Foods or your local fishmonger. Freshness matters most here: the flesh should be opaque, not translucent, and smell cleanly of the sea. For the potatoes, Yukon Golds or Russets work best—their starchiness ensures crispy edges while staying tender inside. The onions should be yellow or red, not sweet varieties like Vidalia, as their sharpness complements the cod's delicate flavor. Trader Joe's often carries pre-sliced onions in their freezer section, saving prep time without sacrificing quality.
No white wine on hand? Dry chicken or vegetable broth works equally well—just reduce the liquid by half before adding to the pan. Fresh herbs wilting? Dried dill or parsley at one-third the amount maintains the herbaceous notes, though fresh is ideal. The lemon juice can be substituted with white wine vinegar in a pinch, though it lacks the bright acidity. For the olive oil, avoid light or refined varieties—look for labels indicating extra-virgin with a harvest date within the last year. The butter should be cold and cubed when added at the end to create a luxurious finish.
This dish reheats beautifully—simply cover with foil and warm in a 350°F oven for 10-15 minutes. Store leftovers in an airtight container for up to 3 days, though the flavors deepen overnight. For meal prep, portion the potatoes and onions separately from the cod to maintain texture. The cod can be baked ahead and kept at room temperature for up to 2 hours before serving, though it's best enjoyed fresh from the oven for peak tenderness.
Why You'll Love This Recipe
- One-Pan Magic: I swear by this recipe for lazy nights—just toss everything on a sheet pan, drizzle with olive oil and wine, and let the oven do the work. No chopping boards, no pots, no stress. The potatoes caramelize right next to the flaky cod, and honestly? That’s my kind of cooking.
- Wine-Infused Richness: The splash of dry white wine in the olive oil doesn’t just add depth—it transforms the dish. The onions turn sweet and jammy, the cod stays tender but gets that subtle, savory lift, and the whole thing tastes like it simmered for hours. (Between us, it’s the secret weapon.)
- Meal Prep Hero: This bakes up beautifully for lunches—just reheat the portions, and the flavors get even better the next day. My kids grab it straight from the fridge for school lunches, and I’ve even packed it for work. The potatoes stay sturdy, the cod doesn’t dry out, and it’s always a hit. (Yes, even on a Tuesday night.)
- Budget-Friendly Feast: Cod’s affordable, potatoes are a staple, and onions stretch the flavor without breaking the bank. A single sheet pan serves four, and leftovers reheat like a dream. I’ll be real: this is the kind of dish that makes me feel like I’m feeding a crowd without the grocery bill to prove it.
Step-by-step instructions for baked cod with potatoes and onions
This one-pan method delivers perfectly flaky cod with crispy potatoes and caramelized onions—minimal effort, maximum bistro-style flavor.
Prep and Season the Vegetables
Preheat your oven to 400°F. In a large bowl, combine the 1.5 lb russet potatoes (cut into 1-inch chunks), 2 whole yellow onions (thinly sliced into rings), 4 cloves garlic cloves (minced), 1.5 tsp diamond crystal kosher salt, and 0.5 tsp freshly ground black pepper. Toss thoroughly to coat the vegetables evenly with the seasoning.
Spread the seasoned potatoes and onions on a large, rimmed baking sheet in an even layer. Drizzle with the 0.25 cup extra-virgin olive oil and toss again to ensure everything is well-coated. Roast for 15 minutes until the potatoes begin to soften and the onions start to caramelize at the edges. This initial roasting builds flavor and prevents soggy vegetables later.
Create the Marinade and Prepare the Cod
While the vegetables roast, prepare the marinade by combining the 0.5 cup dry white wine, 2 tbsp lemon juice, 0.25 cup chopped fresh dill, and 0.25 cup chopped fresh parsley in a small bowl. Whisk until fully integrated, then taste and adjust seasoning if needed—this marinade will infuse the cod with bright, herbaceous notes.
Pat the 2 whole cod fillets (skin-on) dry with paper towels to promote crispiness. Place the fillets in a separate bowl and pour the marinade over them, ensuring they're fully coated. Let the cod marinate for 10 minutes while the vegetables continue roasting. This brief marinade enhances the fish's natural sweetness without overpowering its delicate flavor.
Arrange and Bake the One-Pan Meal
After the initial 15 minutes of roasting, remove the baking sheet from the oven. Arrange the marinated cod fillets on top of the potatoes and onions, skin-side down. The residual heat will help the fish begin to cook gently without overcooking. Pour any remaining marinade from the bowl over the top of the cod to keep it moist.
Return the baking sheet to the oven and bake for an additional 12-15 minutes, or until the cod reaches an internal temperature of 145°F and flakes easily with a fork. The potatoes should be tender with crisp edges, and the onions should be deeply caramelized. The cod's skin should be golden and crisp, while the flesh remains moist and tender.
Finish with Butter and Garnish
Once the cod is fully cooked, remove the baking sheet from the oven. Immediately dot the top of each fillet with 1 tablespoon unsalted butter, allowing it to melt slightly and create a rich, velvety finish. The butter adds a luxurious touch and helps distribute any remaining juices back into the fish.
Garnish the dish with the remaining 0.25 cup chopped fresh parsley for a pop of color and freshness. Let the one-pan meal rest for 2-3 minutes before serving—this allows the juices to redistribute, ensuring every bite is moist and flavorful. Serve directly from the baking sheet for a rustic bistro presentation.
Pro Tips For Making Baked Cod With Potatoes And Onions
- PARBOIL POTATOES FIRST: I used to skip this and wondered why my potatoes stayed dense and flavorless. Cut them into even 1-inch chunks, boil for 5 minutes, then drain—this guarantees they’ll crisp up in the oven instead of turning to mush.
- SALT THE COD LIKE IT’S 1950: Cod’s delicate, so don’t skimp: season both sides with ½ teaspoon of salt per fillet before baking. Let it sit 10 minutes uncovered—this keeps it from curling and ensures the seasoning sticks.
- DON’T OVERCROWD THE PAN: I learned this the hard way—packing the baking dish too tight steams the potatoes and turns them soggy. Leave 1-inch gaps between potatoes and onions; if needed, bake in batches.
- DEGLAZE WITH WINE AFTER: After the potatoes and onions brown, pour in that white wine after removing the pan from the oven. Let it sit for 2 minutes, then scrape up the fond—this adds depth without drying out the cod.
Regional styles of baked cod with potatoes and onions
French Bistro Twist
In French bistros, this dish often features crispy duck confit instead of cod, but cod works beautifully with the same technique. The French version includes white wine reduction drizzled over the top before serving, adding depth.
I like to finish with a sprinkle of fresh thyme alongside the parsley for that classic bistro aroma. 🌿
New England Coastal Style
New England cooks often add clams or mussels to the pan during the final 10 minutes of baking, letting them steam open with the cod's juices. For extra richness, substitute half-and-half for the white wine in the marinade.
A sprinkle of old Bay seasoning (about ½ tsp) elevates the dish with its signature coastal flavor profile.
Mediterranean Herb Focus
Swap the dill for fresh oregano and thyme (about 1 tbsp each) to create a Mediterranean-inspired version. Add cherry tomatoes (halved) to the pan with the potatoes and onions for a brighter, vegetable-forward dish.
A drizzle of balsamic glaze before serving adds a sweet-tangy contrast that Mediterranean cuisine loves. 🍅
German-Inspired Potato Topping
For a heartier German-style take, top the baked cod with thinly sliced potatoes (instead of chunks) and caramelized onions in a separate layer before baking. Add 2 tbsp beer (like Heineken) to the marinade for a malty depth.
Finish with crispy fried onions on top—this version feels like a comforting Sunday dinner. 🍺
Southern U.S. Lemon-Pepper Crunch
Southern cooks often finish this dish with a lemon-pepper crust on the cod. After baking, sprinkle the fillets with 1 tbsp lemon zest and 1 tbsp cracked black pepper, then broil for 2-3 minutes until slightly charred.
The contrast of crispy skin and zesty topping makes this a Southern favorite. 🌶️
Scandinavian Dill & Mustard
Scandinavian versions incorporate Dijon mustard (about 1 tbsp) into the marinade for a tangy kick. Add pickled red onions (about ¼ cup) on top before serving for a sweet-sour balance.
The dill becomes the star here, with 2 tbsp fresh dill chopped finely over the dish. This version feels fresh and vibrant, perfect for spring. 🌸
Nutrition facts
Frequently asked questions
Can I use frozen cod for this recipe?
Thaw the cod fillets overnight in the refrigerator before using. For a quicker method, place the sealed package in cold water for 30 minutes per inch of thickness, changing the water every 10 minutes. Never thaw at room temperature, as this can promote bacterial growth and affect texture. Pat the fillets completely dry before marinating to ensure crispy skin.
How do I know when the cod is fully cooked?
The cod is perfectly done when it reaches an internal temperature of 145°F and flakes easily with a fork. The flesh should look opaque and pull away cleanly from the skin. For skin-on fillets, the skin should be golden and crispy. Overcooking by even 1-2 minutes can make the fish dry, so use a meat thermometer for accuracy.
What if my potatoes are still hard after baking?
If the potatoes remain undercooked, return the pan to the oven for an additional 10-15 minutes at 400°F, covered with foil to trap steam. For next time, cut potatoes into slightly smaller chunks (about ¾-inch) or parboil them for 5 minutes before baking to ensure even cooking. The onions should be tender but not mushy—adjust baking time accordingly.
Can I make this dish ahead of time?
Yes! Bake the potatoes and onions 1 day ahead and store them in an airtight container in the refrigerator. Reheat them in the oven at 375°F for 15 minutes before adding the cod. For the cod, marinate it up to 4 hours ahead, then bake it fresh before serving. The flavors deepen when components are prepared separately and combined later.
What’s the best way to reheat leftovers?
Reheat cod and potatoes together in a 350°F oven for 10-15 minutes, covered with foil to prevent drying. For a crispier texture, place the potatoes and onions on a baking sheet and reheat them uncovered for 5 minutes after warming the cod. Avoid microwaving, as it can make the fish rubbery. Leftovers keep well for 3 days in the fridge.