Cook the rice in salt water, drain. Cut cabbage coarsely. Cook in 1/8 l salt water for about 5 minutes. Cut tomatoes in half. Cut 2 slices from the lemon, squeeze the rest. Chop onion. Sprinkle fish with lemon.
Fill cabbage with stock, tomatoes, onion, lemon slices and capers into an ovenproof dish. Season fish, place on top. Pour breadcrumbs, dill and oil over it. Bake in a hot oven (electric cooker: 225 °C/circulating air: 200 °C/gas: level 4) for about 15 minutes.
Dress everything.