Ingredients :

• Cod and salmon — Two fishes with very distinct characters: the cod flakes into large white petals, firm yet tender, while the salmon keeps a fattier, melting texture. Together, they provide variety in every spoonful. Get thick fillets if you can — thin slices break apart in the broth before they’re even cooked.
• Mussels — Buy them alive, the same day. They must be closed before cooking and open during. Those that stay stubbornly closed after cooking are discarded without negotiation. Their cooking water will perfume the whole broth with a powerful hit of iodine — that’s what gives it that seaside taste.
• Leeks — The leek is the soul of simmered dishes. It melts gently, becomes almost silky, and brings a vegetable sweetness that balances the marine side. Cut them into chunks that aren’t too thin — they need to hold up during cooking, not dissolve into filaments.
• Vegetable or fish stock cube — A good cube is more than enough here — the mussel water and vegetables do the rest. If you have one on hand, a fish stock cube gives even more depth. But with a classic vegetable cube, the result is already very good.