In a large nonstick skillet over medium high heat, melt the butter or heat the oil until shimmering. Add the onion and cook until clear. Stir in the ham or prosciutto as well as the bell pepper. Cook, stirring until the mixture is hot.
Add the eggs, season to taste with salt and pepper, and cook. Once the eggs start to turn white around the edges, stir the eggs to scramble. Continue to cook and stir until the eggs are cooked to your preference. Serve immediately.