salt and pepper
In a medium bowl, whisk together eggs and milk. Stir in tomatoes.
Heat butter in a large skillet over medium-high heat. When butter melts and bubbles, add eggs. Let eggs sit until edges cook, about 1 minute. Reduce heat to medium-low and stir constantly.
When eggs begin to hold together but are still runny, add cheese and onions. Season with salt and pepper to taste. Cook until eggs set.