1In 8-inch nonstick skillet, heat oil over medium-high heat. Add bell pepper, onion and mushrooms to oil. Cook 2 minutes, stirring frequently, until onion is tender. Stir in spinach; continue cooking and stirring just until spinach wilts. Remove vegetables from pan to small bowl.
2In medium bowl, beat egg product, water, salt and pepper with fork or whisk until well mixed. Reheat same skillet over medium-high heat. Quickly pour egg mixture into pan. While sliding pan back and forth rapidly over heat, quickly stir with spatula to spread eggs continuously over bottom of pan as they thicken. Let stand over heat a few seconds to lightly brown bottom of omelet. Do not overcook; omelet will continue to cook after folding.
3Place cooked vegetable mixture over half of omelet; top with cheese. With spatula, fold other half of omelet over vegetables. Gently slide out of pan onto plate. Serve immediately.