Wash, clean and halve the tomatoes. Place on a baking tray lined with baking paper. Wash the thyme, dab dry and put aside some to garnish. Spread the rest of the thyme on the tomatoes, season with salt and pepper.
Sprinkle tomatoes with cheese. Sprinkle with 2 tablespoons of oil. Clean, wash and chop the celery. Peel and chop onion. Heat 1 tablespoon of oil in a wide saucepan. Fry the onion in it.
Add celery. Add 150 ml water, bring to the boil and stir in the stock. Simmer over high heat until the liquid has almost evaporated. Bake tomatoes in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 8-10 minutes.
Wash the fish, dab dry. Whisk eggs, season with salt and pepper. Heat 2 tablespoons of oil in a pan. Pull the fish through the egg. Fry in hot oil for 2-3 minutes on each side. Season celery vegetables with salt and pepper.
Arrange fish with vegetables and tomatoes. Garnish with thyme.