Can I use boiled potatoes in Spanish omelette? I have some leftover microwaved potatoes. Can I use these potatoes in Spanish omelette? Also, I read that tomatoes are not part of "authentic" Spanish omelette. Is that true?
You shouldn't use boiled potatoes as you have to fry them.

This is a good recipe, and no, tomatoes are not part of "authentic" Spanish omelette. In Spain we call it "Potato omelette" an the only ingredients are eggs, potatoes, olive oil, salt and sometimes onion.