Wash and skin the tomatoes. Dice the flesh coarsely.
Heat 2 tablespoons of the olive oil in a pan. Add the diced peppers and cook gently over a low heat until soft. Add the diced tomatoes and the chopped garlic. Season and sprinkle with 1 pinch of chilli powder. Cover and cook gently for around 15 minutes. Add the olives towards the end of cooking.
Meanwhile, heat the remaining oil in a pan, add the chopped onions and brown gently, stirring regularly. Add the rice and mix well. Pour in the warm vegetable stock. Bring to simmering point and add the other pinch of chilli powder, season and cover. Simmer for around 15 minutes.
Serve the hot rice accompanied by the vegetables.