Wash and dice eggplants. Peel and slice the onion. Peel and cut the tomatoes into eighths. Bring the quinoa to the boil with 3/4 liter of salted water and cook on a low heat for 15 minutes.
Heat the oil in a large pan or in a wok. Fry the eggplant and onion in it over medium heat while stirring for about 3 minutes. Add the tomatoes and capers and heat. Season to taste with vinegar, salt and pepper.
Season the quinoa with herbs, salt and pepper and serve with the vegetables.