Heat oil in 10-inch skillet just until hot.
Fry tortilla wedges over medium-high heat until crisp, stirring frequently.
Reduce heat and add onions, cooking until onions begin to soften. Add beaten eggs, salt and pepper. As eggs begin to set at the bottom and sides, gently lift cooked portions with spatula so that uncooked egg can flow to bottom. Do not stir. When nearly set, sprinkle with the cheese, cover, and heat until cheese has melted and egg is cooked to desired doneness.