Pour a lug of olive oil in a large frying pan and sauté the leeks until wilted. Add the mushrooms, the tomatoes, a pinch of salt and pepper and continue to sauté until the liquids are absorbed. Remove from the heat.
Beat the eggs with the milk (if added), a pinch of salt and finely chopped basil or parsley leaves. Toss in the crumbled feta cheese, mash with a fork, then stir to combine with the egg mixture.