In a small bowl, combine egg whites with garlic powder, salt and pepper.
Heat 1 teaspoon of olive oil in a non-stick skillet over medium heat.
Once hot, add diced onion, chopped spinach and chopped sun-dried tomatoes. Sauté over medium heat to wilt the spinach.
Pour into the pan the egg white mixture. Stir occasionally, cooking until the egg whites are fully set and cooked through.
Warm up the tortilla, in a skillet or in the microwave.
Spread the egg white mixture evenly on top of the warmed tortilla, then sprinkle with crumbled feta cheese.
Fold the sides of the tortilla over the filling and then roll it up tightly to form a wrap.
Serve immediately or let cool and store for later (read storage notes for more details*).