Wash the fish, cut into 4 pieces. Sprinkle with lemon juice, season lightly with salt and pepper. Wash, clean, quarter and seed the tomatoes. Cut the flesh into strips.
Clean the fennel, wash it, cut it to the stalk and cut it very thin. Chop the fennel greens. Peel and finely chop the onion. Heat oil in a pan. Fry the fish pieces on each side for about 3 minutes at medium heat, remove.
Add the onion, fennel and tomatoes to the pan. Season with salt and pepper, pour on broth, add capers. Place the fish on top and simmer covered for about 5 minutes. Season again and sprinkle with fennel green.