Preheat the oven to 100°C. Lay the salmon on baking paper, lightly salt and rub with olive oil. Bring the fish stock to the boil, stir in the crème fraîche slowly, stop cooking and just keep warm. Refine with lemon juice and season to taste.

Put the salmon in the oven for 5 minutes.

For the spinach: heat a pot with the olive oil, add the spinach, onions and garlic. Season and cook briefly. Drain the spinach in a sieve.

Gently squeeze out the spinach and place in a deep plate. Pour the sauce around the spinach. Optionally, refine the sauce with the herb oil.

Lay the salmon on top of the spinach and garnish with a generous dollop of Osetra Imperial caviar.