Clean, wash and chop the pepper and celery. Peel onion and garlic. Cut onion into thin slices, chop garlic. Wash and chop the tomatoes. Wash thyme, dab dry, remove leaves.
Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Heat oil in a pan. Sauté peppers, celery and onion for approx. 3 minutes. Fry tomatoes, garlic and olives for another 1-2 minutes.
Add 100 ml of water, broth and thyme. Simmer for about 3 minutes. Season to taste with salt, pepper and lemon juice and place in an ovenproof dish.
Rinse fish, pat dry, divide into 4 pieces and season with salt and pepper. Place on the vegetables. Cook in a hot oven for about 20 minutes. Baguette tastes good with it.