Mix together a good amount of extra virgin olive oil, a good amount of lemon juice, a pinch of salt, and some black pepper. Brush the fish with it, then roll it in chopped marjoram or oregano. Cook the fillets in a very hot grill pan (make sure it’s really clean, to prevent the fish from sticking).
If the fillets are 2 cm thick, they will only need about 2 minutes of cooking. If the fish breaks, it’s not a problem, as it will be flaked anyway. If it still has its skin, cook it directly on the skin, it will stick less. Once cooked, set it aside on a warm plate.
To make the salad, slice the tomatoes finely and season with salt and pepper. Then, place them on the plates. Slice the fennel bulb finely and put it in a bowl with the extra virgin olive oil and lemon juice. Season with salt and pepper, then divide it among the tomato portions. To finish, flake the fish with a spoon. Share it on top of the fennel plates, drizzle with a little balsamic vinegar, and add a bit of hot pepper, if desired.