In a large bowl, whisk the eggs, water, salt and pepper; set aside.
Place a 10-in. cast-iron skillet over medium-high heat. In the skillet, saute onion and jalapeno in butter until tender. Add egg mixture; cook and stir until almost set. Stir in cheese and chives; cook and stir until eggs are completely set.
Wear disposable gloves when cutting hot peppers; the oils can burn skin. Avoid touching your face.