In A Large Bowl, Whisk The Egg Whites And Eggs. Add The Sour Cream, Milk, Onions, Salt, Pepper And Food Coloring If Desired. Pour Into A Large Nonstick Skillet Coated With Nonstick Cooking Spray; Cook And Gently Stir Over Medium Heat Until Eggs Are Completely Set. Remove From The Heat. Sprinkle With Cheese; Cover And Let Stand For 5 Minutes To Allow Cheese To Melt.