Preheat oven to 80 °C. Rinse the salmon inside and out under cold running water and dry well with kitchen roll. If the fish is too big for the baking tray, cut the head and/or tail into small pieces.
Clean and rinse the fennel, set aside the greens and slice the fennel into thin slices. Rinse the tomatoes.
Remove the skin from the garlic, cut 2 garlic cloves into slices. Sauté the fennel and garlic slices in a large frying pan in 5 tbsp oil for about 5 minutes and season with sea salt and pepper. Spread the fennel evenly on the baking sheet. Add the tomatoes to the frying pan, sauté briefly and also spread evenly on the tray. Season the salmon inside and out with salt and season with pepper. Rinse the lemon, rub dry and cut into slices. Rinse the kitchen herbs, shake dry and chop coarsely. Lightly crush the remaining 3 garlic cloves.
Stuff the lemon, culinary herbs and garlic cloves into the belly cavity of the fish. Place the salmon on the fennel vegetables and drizzle with the remaining oil. Cook on the second rack from the bottom for about 1 hour (perhaps use a digital thermometer to measure the core temperature of the fish, it should be about 60 °C, then the salmon is still slightly glassy inside).
Take out the salmon, remove the skin and fillet the fish.
Season with a little fleur de sel and arrange on the fennel vegetables.
According to desire and