Almost any food can fill an omelet – vegetables or fruits; grains, including rice; lean meat, poultry, fish or seafood; yogurt or cheeses of all kinds. To invent your own omelet filling, use one or more filling ingredients to total about 1/3 to 1/2 cup for each omelet. Flavor the omelet, the filling or both with about 1/8 to 1/4 teaspoon of your favorite herb, spice or seasoning blend, or a dip, salad dressing, soup or other flavoring mix.
Omelets cook very quickly, so heat refrigerator-cold fillings to serving temperature or fully cook raw foods before you begin cooking the eggs. Fill an omelet right after you’ve finished cooking it. At this point, the omelet will be hot enough to melt cheese and warm some filling ingredients, such as yogurt, peanut butter, jelly or diced or sliced fruit.