In a large skillet, heat canola oil over medium heat. Saute bell pepper, mushrooms, scallions and garlic for 4-5 minutes, until tender.
Add spinach, tomatoes and fresh herbs. Stir occasionally until spinach is wilted, about 2 minutes. Season to taste with salt and pepper.
Meanwhile, heat a smaller skillet over low heat. Crack 1 egg and 2 egg whites into 4 separate bowls for individual omelets and beat until smooth. Season each with salt and pepper.
Spray the skillet with Pam and pour one bowl of eggs into the hot pan. Cover with a top and let cook for 5-7 minutes, until just a little runny on top. Add 1 Tbsp of cheese and cover to melt cheese.
When cheese is melted and egg is cooked through, add a quarter of the veggie mixture and fold the omelet.
Repeat steps 4 & 5 until all omelets are cooked.