Wash asparagus and cut off tough ends.

Chop asparagus spears into small pieces.

Melt butter in a frying pan over medium heat.

Saute finely chopped onion in butter for 10 minutes, until softened.

Add chopped asparagus and water to the pan.

Cover the pan and cook for 10 minutes, until asparagus is tender.

In a separate bowl, thoroughly combine beaten eggs, finely chopped fresh cilantro, cayenne, salt, and pepper.

Pour the egg mixture into the frying pan with the asparagus and onion.

Stir-fry briefly until the eggs are cooked through and the omelet is set.

Serve hot.