Pre-heat oven to 375°F. Heat olive oil over medium heat in a large cast iron skillet and sauté onion until soft and translucent. Add garlic and vegetables and cook until tender. Season with salt/pepper and set aside in a bowl.
In a large bowl, beat the eggs with soy milk, flour, salt, and pepper until combined. Then, add the sautéed vegetable and stir to combine.
Spoon the egg mixture into greased muffin tins.
Bake for 20 minutes, rotating the tray at the halfway point. Let muffins cool in the pan for a few minutes. Enjoy!