When you think of a fish gratin, you might picture a creamy casserole dish bubbling with cheese and tender chunks of white fish. It’s warm, comforting, and satisfying. But what if you could keep all that comfort and add something a little… unexpected? That’s where seaweed comes in.
This fish gratin with seaweed brings together the best of both worlds: the creamy richness of a traditional fish gratin and the bold, umami-packed depth of ocean flavors. Whether you’re a seasoned seafood lover or just looking for new ways to cook fish at home, this recipe will surprise and delight you.
Why Seaweed?
Seaweed might not be a staple in every kitchen yet, but it absolutely deserves a spot. Used for centuries in Japanese, Korean, and coastal cuisines around the world, seaweed is a true superfood. It’s rich in iodine, iron, magnesium, and antioxidants—and it brings a subtle salty complexity that enhances fish and shellfish beautifully.
Unlike stronger fish or shellfish, seaweed provides that deep marine flavor without overpowering the dish. It’s perfect in a creamy bake, where it softens slightly but still offers a light chew and vibrant taste.
Adding seaweed to your fish and seafood gratin isn’t just trendy—it’s smart, flavorful, and surprisingly easy.
Ingredients for 4 Servings
- 1 lb (500 g) white fish fillets (cod, haddock, pollock, or hake)
- 1 small handful dried seaweed (wakame, dulse, or sea lettuce)
- 2 shallots, finely chopped
- 1 garlic clove, minced
- ¾ cup heavy cream
- ⅓ cup milk
- 1 tablespoon Dijon mustard
- ¾ cup shredded cheese (Emmental, Gruyère, or Parmesan work great)
- Juice of half a lemon
- Olive oil
- Salt and pepper
🧂 Optional Add-Ins
- A handful of peeled shrimp or a few scallops for a heartier fish and seafood gratin
- 2 tablespoons breadcrumbs for an extra-crispy top layer
- A pinch of chili flakes if you like a subtle heat
Tools You’ll Need
- Mixing bowls
- A medium skillet
- A small saucepan
- An oven-safe baking dish
- Knife and cutting board
- A whisk or spoon for mixing sauce
How to Make Fish Gratin with Seaweed
1. Soak the Seaweed
Place the dried seaweed in a bowl of warm water. Let it sit for about 10 to 15 minutes. It will expand and soften. Once rehydrated, drain and chop roughly if needed.
2. Sauté the Fish
Heat a bit of olive oil in a skillet. Add shallots and garlic and cook for 2 minutes until fragrant. Add your fish fillets, cut into chunks, and cook gently for 5–7 minutes. Add a squeeze of lemon juice. Season lightly with salt and pepper. Remove from heat once the fish is opaque but not fully cooked—it will finish in the oven.
3. Prepare the Creamy Sauce
In a saucepan, combine cream, milk, and mustard over low heat. Stir until warm, then add in the soaked seaweed. Season with salt and pepper. The sauce should be smooth, lightly thickened, and fragrant.
4. Assemble the Gratin
Layer the cooked fish evenly into a baking dish. Pour the seaweed cream sauce over the top. Sprinkle with shredded cheese. Add a layer of breadcrumbs if you like a crunchy topping.
5. Bake Until Golden
Bake in a preheated oven at 350°F (180°C) for about 25 minutes, or until the top is golden brown and bubbling. Let it cool slightly before serving.
What to Serve with Fish Gratin
This dish is versatile and pairs wonderfully with:
- Steamed white rice or wild rice
- Mashed potatoes or sweet potato mash
- Quinoa, bulgur, or couscous
- A crisp fennel salad with lemon vinaigrette
- Roasted carrots or green beans for a complete meal
For drinks, a crisp dry white wine like Sauvignon Blanc, Muscadet, or Chablis is ideal.
Health Benefits at a Glance
- White fish provides lean protein, vitamin B12, and omega-3s.
- Seaweed is rich in iodine, calcium, and antioxidants, and may help support thyroid health.
- Cream and cheese give the dish its indulgent texture, but you can adjust the richness by using lighter dairy alternatives.
This fish gratin with seaweed is proof that indulgent comfort food can also be nutritious.
Make It Your Own
This recipe is easy to customize depending on your taste and what you have in your kitchen.
✅ No seaweed? Substitute chopped spinach, kale, or sautéed leeks.
✅ Lactose-free? Use oat cream or coconut milk, and dairy-free cheese.
✅ More seafood? Add shrimp, mussels, or smoked salmon for a deluxe fish and seafood gratin.
✅ No oven? Finish it in a stovetop skillet with a lid—less crispy on top but still delicious.
FAQ –
Can I make it ahead of time?
Yes! You can prep the dish up to the baking step, cover it, and store it in the fridge for 24 hours. Then just bake it when you’re ready. You can also freeze it before baking—just allow a bit more time in the oven.
Which fish works best?
White flaky fish like cod, pollock, haddock, or hake are ideal. They cook quickly, absorb flavor well, and hold their shape during baking. You can also use salmon or trout for a richer taste.