Beat eggs and stir in onions, green chillies, coriander leaves, milk, salt and pepper powder. Divide the mixture into four equal portions. Place one tablespoon of butter in a flat microwave dish and heat, uncovered, on Microwave HIGH (100%) for twenty seconds.
Spread evenly and pour one part of egg mixture, ensuring that it spreads evenly too. Cook, uncovered, on Microwave HIGH (100%) for three minutes. Allow to stand for one minute. Serve immediately. Repeat the process for the remaining omelets.