Melt the margarine or butter in a medium nonstick skillet over medium-high heat. When the margarine or butter is fully melted and starting to bubble lightly, add the sliced green onions, the medium green bell pepper, the medium red bell pepper and the medium yellow bell pepper. Cook for 2 to 3 minutes, stirring occasionally, until the vegetables are crisp-tender.

While the vegetables cook, add the eggs, milk, salt and pepper to a medium bowl. Beat well until the mixture is smooth and evenly blended, with no streaks of egg white remaining.

Pour the egg mixture evenly over the vegetables in the skillet. Reduce the heat to medium; cook for 4 to 6 minutes, stirring frequently, until the eggs are set but still moist (no longer runny).

To serve, warm the tortillas if desired, then spoon the egg and pepper mixture down the center of each tortilla. Sprinkle with shredded cheddar or monterey jack cheese, then roll up the tortillas to form burritos and serve hot.