Microwave potato to cooked-but-firm state, normally 3 minutes.
Saute onions, then peppers in a few drops of olive oil, and remove with slotted spoon. Cut potato into half-inch cubes. Add potatoes and rosemary to pan with salt and pepper to taste and leave on low heat until guests are settled. Stir occasionally.
Add potatoes, pepper and onions to oiled 6-inch cast iron pan. Pour eggs over vegetables. Top with tomato slices and sprinkle on Parmesan. Cook on medium heat.
When eggs firm around edges, move pan to broiler. Allow to cook until top resembles souffle or well-done pizza. Remove, check to make sure center is done, cut in half and serve.