Prepare peppers, mushrooms and/or onions.

Heat oil in small omelette or frypan on medium-high heat setting. Add vegetables and cook for 3 minutes, stirring occasionally.

Break eggs into a small bowl and whisk.  Pour over vegetables. Tip and swirl pan so all vegetables are covered. Season with salt and pepper, and cover. Cook for about 3 minutes, until top of egg mixture has firmed. Flip omelette. Add cheese and/or salsa if desired. Fold omelette in half over cheese. Cover and cook until cheese/salsa is melted, about 2 minutes.

Remove from pan and serve.