Cook bacon in an ovenproof nonstick or cast-iron skillet over low heat until crisp, 2-3 minutes. Using a slotted spoon, transfer bacon bits to paper towels to drain, then reserve. Add vegetable oil to the bacon fat in the pan if needed to make 2 tablespoons.
Raise heat to medium-low and add onion. Cook slowly, stirring occasionally, until translucent, 8-10 minutes. Add vegetables and sauté until lightly browned, 8-10 minutes more. Meanwhile, beat eggs until blended and season with 1/2 teaspoon salt and 1/4 teaspoon pepper. Pour them over the ingredients in the skillet, and add the crisp bacon bits to the mixture, stirring gently.
Preheat broiler. Reduce heat to low, cover skillet, and cook until eggs are nearly set, 6-8 minutes. Remove cover and place the skillet under the broiler to brown the eggs lightly, about 3 minutes, while watching carefully. Cut into wedges and serve at once.
Makes 4 servings