Melt butter in large non-stick pan set over medium heat. Add onion, ginger, salt and pepper. Cook, stirring often until softened, about 5 minutes. Whisk eggs with curry paste and pour into pan.
Scatter peas, tomato and chili pepper (if using) over eggs. Cook until starting to set on bottom, about 2 minutes. Cook, stirring constantly until small curds are set, but still tender, about 3 minutes.