Heat the olive oil in a large non-stick skillet over medium heat until shimmering.
Add the diced bell pepper and red onion to the skillet and sauté for 3-4 minutes until softened.
Add the cherry tomatoes and spinach, cooking for another 1-2 minutes until the spinach wilts and the tomatoes just begin to soften.
In a bowl, whisk together the egg whites, garlic powder, salt, and pepper until slightly frothy.
Pour the egg white mixture into the skillet with the vegetables and reduce heat to medium-low.
Gently stir the eggs with a spatula, pushing them from the edges to the center, cooking for 3-4 minutes until soft curds form and the eggs are just set but still creamy.
Remove from heat, garnish with fresh herbs if desired, and serve immediately.