Drain the beans and rinse thoroughly with cold water. Drain and transfer to a bowl. Cut the onions into fine strips, sprinkle with salt, let stand for about 10 minutes and then squeeze out well. Add to the beans with the tomatoes, half of the olives, parsley and chilli flakes and mix well.
Mix a marinade with lemon juice, olive oil and a little salt and pepper and pour over the salad. Mix well and let the salad stand for a while.
Garnish with the eggs and the remaining olives to serve.