Oven-Baked Cod with Root Vegetables and Simple Mustard Sauce - fish, baked recipe

Oven-Baked Cod with Root Vegetables and Simple Mustard Sauce

This delightful autumn dinner combines tender oven-baked cod with roasted root vegetables and a creamy mustard sauce. The sweet earthiness of the vegetables perfectly balances the fresh, tangy flavors of the sauce, creating a wholesome and satisfying meal.

Instructions

  1. 1

    Preheat your oven to 220°C (200°C fan).

  2. 2

    Peel and dice the potatoes and root vegetables into thumb-sized pieces.

  3. 3

    Toss the vegetables with olive oil, salt, and pepper until well coated.

  4. 4

    In a bowl, prepare the coating by mixing parmesan, breadcrumbs, chopped herbs, and oil into a coarse mixture. Set aside.

  5. 5

    Spread the seasoned vegetables on a parchment-lined baking sheet and roast for 25-30 minutes. When 12-15 minutes remain, remove the tray and place cod fillets on top of the vegetables. Evenly distribute the parmesan coating over the fish.

  6. 6

    For the mustard sauce: In a bowl, whisk together mayonnaise, Dijon mustard, lemon juice, fresh herbs, salt, and pepper. Add sriracha if desired for heat.

  7. 7

    Taste the sauce and adjust with additional lemon juice and mustard as needed.

  8. 8

    Arrange the roasted vegetables on plates with the cod on top.

  9. 9

    Drizzle with the mustard sauce and garnish with fresh herbs before serving.

Per average serving

930
Calories
kcal
42.8
Protein
g
76.7
Carbs
g
51.5
Fat
g
12.1g
Fiber
24.2g
Sugar
987mg
Sodium

Tips from the kitchen

  • Cut the potatoes and root veg the same size, about thumb-sized, or the harder pieces stay crunchy while the softer ones turn to mush. The 25-30 minute roast assumes they're roughly even.
  • Give the cod a quick pat with paper towel before it goes on the vegetables. A drier surface means the parmesan and breadcrumb coating sticks instead of sliding off.
  • Don't add the fish too early. It only wants 12-15 minutes at the end. Cod is done when it flakes with a fork and turns opaque all the way through, so check the thickest part.
  • Mix the mustard sauce while the vegetables are roasting and let it sit. The flavors settle and the mustard mellows a bit, so taste again right before you spoon it out.
  • If your cod fillets are thin at the tail end, tuck that thin part under itself so the piece is more even. Saves you from overcooked edges.

Ways to vary it

  • Salmon works in place of the cod if that's what you have. It's more forgiving on timing and the mustard sauce goes well with it.
  • Swap the sriracha for a pinch of chili flakes, or leave the heat out entirely if you're cooking for kids. The sauce holds up fine either way.
  • For the root veg mix, parsnip and carrot lean sweet while celeriac and turnip bring something earthier. Mix whatever's in the drawer.

Storage & leftovers

Keeps in the fridge for up to two days in a sealed container, though the breadcrumb coating softens overnight. The fish doesn't freeze well, it goes watery, so eat it fresh. Reheat the cod and veg in a 180°C oven for about 10 minutes rather than the microwave, which dries out the fish, and keep the mustard sauce cold on the side.

What to serve with it

A wedge of lemon and some crusty bread to catch the sauce is all it needs. A cold beer or a glass of dry white rounds it out.

UC
By Untrained ChefPublished 3 February 2026 · Updated 11 July 2026