Combine first 4 ingredients in a medium bowl, stirring with a whisk.
Heat a small nonstick skillet coated with cooking spray over medium-high heat. Add mushrooms and bell pepper; sauté 5 minutes. Pour egg mixture into pan; top with potato (do not stir). Cover, reduce heat to medium-low, and cook 8 minutes or until center is set.
Spread Classic Pesto over omelet. Loosen omelet with a spatula, and cut in half. Slide omelet halves onto plates.