Cut the onions into rings and the peppers into strips. Mix the salt, garlic, ginger and chili powder in a small bowl. Add lemon juice and work everything into a paste.
Place the prawns in a bowl of cold water and set aside to defrost. Drain well.
Heat the oil in the pan (with a relatively high rim, otherwise a saucepan). Add the onions and fry until golden brown. Reduce the heat. Add the spice paste to the onions and stir-fry for 3 minutes.
Add the peppers and tomatoes with the juice and cook for 5 - 7 minutes, stirring occasionally. Add the thawed prawns to the saucepan and simmer the mixture for about 10 minutes, stirring occasionally. Garnish with coriander and serve hot.
Rice is also suitable as a side dish. B. Tagliatelle and green salad.