Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Line a baking tray with baking paper. Rinse the shrimps, dab dry and cut them in half lengthwise, removing the dark gut if necessary. Mix with 2 tablespoons of olive oil, some salt and pepper on the baking tray. Pre-cook in a hot oven for about 5 minutes.
Meanwhile bring 3-4 l salted water (1 teaspoon salt per litre) to the boil. Drain capers and olives, chop both roughly. Wash lemon hot, dab dry and cut into thin slices. Wash the herbs, shake dry and chop the leaves coarsely. Wash and halve the tomatoes.
Cook the pasta in boiling salted water according to the instructions on the packet until al dente. Meanwhile peel onions and garlic, chop both finely. Heat 4 tablespoons of oil in a large frying pan. Brown the onions and garlic in it. Add prawns, capers, tomatoes and lemon slices. Fry for 2-3 minutes. Drain the pasta, let it drain for a short time and put it back into the pan. Mix in the shrimp mix, olives, ajvar and herbs. Season to taste with salt and pepper. Sprinkle with parmesan cheese if you like.