Heat the oil in a large nonstick frying pan over moderate heat. Add the capsicums, onion, garlic and a pinch of salt, and cook for 5 minutes or until the capsicums are crisp-tender. Add the tomato and cook, stirring, for 7 minutes or until the liquid has evaporated.
Meanwhile, combine the whole eggs, egg whites, ricotta cheese, a good grinding of pepper and a pinch of salt in a food processor, and process until smooth.
Pour the egg mixture into the frying pan, reduce the heat to low, and cook, stirring, for 3 minutes or until set.