1. Heat the oil and fry the tortillas for a few seconds on each side. Remove and drain. Keep the tortillas warm.
2. Halve, pit and peel the avocado, then cut into slices. Dip the tomato in boiling water, then skin and chop coarsely.
3. Melt the butter in a frying pan and fry the eggs, in batches, sunny side up.
4. Place two tortillas on four plates, slip an egg on each and top with sliced chilies, avocad and tomato. Season and serve garnished with cilantro.