Thaw the prawns, then put them in a colander, sprinkle them over and drain well.
Peel and finely chop onions and garlic. Remove the stalk from the tomatoes. Scald tomatoes briefly, peel them, cut in half crosswise and core. Dice the pulp.
Heat the olive oil in a sauté pan, fry the onions and garlic over a moderate heat for 7 minutes until light yellow. Add the tomato cubes and sauté until they disintegrate. Pour in white wine and stock, simmer gently for 10 minutes uncovered. Wash and finely chop the dill and parsley, stir into the sauce. Roughly grate the sheep cheese and stir in. Season the sauce with salt, pepper and saffron. Heat gently until the feta cheese has melted. Add the prawns to the sauce, add lemon juice to taste and heat briefly.