Rinse the lentils in a sieve and drain. Boil with 350 ml of water and the thyme sprig, cook at a moderate temperature for 30 minutes and put aside.
Cut the tomato peppers in half, remove the stems and the core. Rinse the peppers, cut into fine cubes. Remove the peel from the onions and dice them just as finely. Pluck off half of the basil leaves and cut into fine strips.
3. Heat 2 tbsp. oil in a frying pan and sauté the vegetables for 2 min, turning at a moderate temperature, seasoning lightly with salt and freshly ground pepper. Briefly rinse the fillets, dry them between paper towels and sprinkle lightly with salt and pepper on both sides.
Place a little of the vegetable stuffing on each plaice fillet and a few basil strips on top, then roll up and secure the ends with toothpicks. Heat 2 tbsp. oil in a non-stick frying pan, pour in the rolls and fry lightly on all sides over medium heat. Be careful when turning, the fish is very tender and falls apart easily.
Then pour 50 ml of water, add any leftover filling and steam the rolls for 5-6 minutes with the lid closed until soft. Drain the lentils in a sieve and put them in a small bowl.
Rinse the tomatoes, cut them in half, remove the stalks and scrape out the seeds with a teaspoon. Cut the tomatoes into small cubes and add to the lentils. The leaf sala