Squeeze the lemons. Whip lemon juice and 4 tablespoons of oil well together. Peel onion and garlic and dice finely. Pluck some needles from the rosemary. Save the rest for garnishing.
Rinse the thyme, leave a branch behind as well, chop the rest. Mix everything with the lemon oil. Wash the fish, put them in a shallow bowl, pour the marinade over them and leave them in the fridge for about 30 minutes.
Remove from the marinade, dab dry and sprinkle with salt inside and out. Grill or fry under the grill or in 1 tbsp. oil in a pan on each side for 2-3 minutes and keep warm. Heat the marinade briefly as desired and pour over the fish.
Garnish with rosemary, thyme and lemon cut into pieces and serve. Serve with baguette bread.