Although this unique omelette is usually served from the skillet, it is also delicious served cold or at room temperature. Indeed, cooled leftovers of this delectable dish with a glass of amontillado sherry make for a perfect picnic lunch.
While some slice this omelette into bite-size squares and serve it as a tapa, it is more common to see this dish served in more generous portions for lunch or a light supper.
Wash the asparagus and trim them into 1-inch pieces. Bring water to a boil in a saucepan and add the asparagus pieces. Cook for about 2 to 3 minutes or until tender. Drain the asparagus and set aside.
Heat the olive oil over low heat in a 12-inch skillet. Add the chopped onion and garlic and cook until tender. Stir in the asparagus, salt, pepper, and grated cheese.
Reduce the heat to low and pour the beaten eggs into the skillet. Do not stir the mixture. Cook, covered, until the omelette sets, around 15 to 20 minutes. Slice into four portions and sprinkle with lemon juice.
Garnish with sliced tomato and serve.