Rinse the prawns and pat them dry. Wash, quarter, seed and dice the tomatoes. Peel onion and garlic and dice finely. Wash the rosemary and dab dry. Put something aside for garnishing.
Heat the oil in a large frying pan. Fry the prawns for 2 minutes on each side, remove them. Sauté the onion, garlic and rosemary in the frying fat. Add the tomatoes and fry over a mild heat for about 5 minutes.
In the meantime cook Farfalle in boiling salted water for about 9 minutes. Deglaze the tomatoes with white wine and stock, boil down a little. Add the prawns and warm up briefly in the sauce. Season to taste with salt and pepper.
Drain the pasta, let it drain. Serve the pasta with the sauce. Garnish with rosemary set aside.