What are your favorite (healthy/vegetarian) omelette fillings!?

Okay for the egg part (whisked together)….

about a half cup of egg whites,
2 tbsp of soymilk,
a half tsp of baking powder (add fluffiness),
garlic powder,
onion powder,
salt,
pepper,
about a tablespoon of flax seed
sprinkle of nutritional yeast

and for the fillings..

(corn, salsa, beans, fat free cheddar cheese, chili powder, cumin)
(any combo of sauteed onion, tomato, mushroom, broccoli, spinach, or other fresh veggies)
(fat free cream cheese, spinach, mushrooms, little lemon juice)
(Tomato, spinach, Meal Starter crumbles, steak seasoning)

Okay so basically I am totally out of filling ideas. I would love to know what you put in your omelets!!! Whether it is a random combo (spinach, tomato, and certain seasonings) OR it has a theme (southwestern, Chinese, BBQ “chicken”, etc.)

PS. I wouldn’t mind a few avocado-including recipes. im trying to increase my good-fat intake! Thanks!!!