I saw this on a Jamie Oliver show (he is a UK celebrity chef)
Make your omelette mix, roughly, don't beat it too much, pour into a low heat frying pan and immediately add any cut vegies, meat pieces etc that you like, don't stir or try to fold. when the eggs set serve up. I've tried this with bacon, capsicum, mushroom, left over roast potatoes, toms etc. It works. Good way to use left overs for breakfast.