In a pot, sauté the leeks, carrots, and potatoes until they start to soften.
Pour in the fish stock or vegetable broth and let it cook until the potatoes are tender.
Add the salmon fillet to the pot and gently stir.
Incorporate the crème fraîche and fresh dill, then cook for an additional 5 minutes.
Serve the soup with a squeeze of lemon juice on top.
