COOK and stir vegetables in large nonstick skillet sprayed with cooking spray on medium-high heat 5 min. or until crisp-tender. Remove from skillet; set aside.

BEAT whole eggs, egg whites and water with whisk until well blended. Pour into skillet; cover. Cook 6 min. or until egg mixture is almost set but top is still moist. As egg mixture sets, lift slightly with spatula to allow uncooked portion to flow underneath.

TOP with vegetables and cheese. Slip spatula underneath, tip skillet to loosen and gently fold omelette in half. Cover; cook 3 min. or until cheese is melted. Serve topped with salsa.