Heat oil in a pan over medium heat.
Add the onion, tomatoes, spinach, shiitake mushrooms, and broccoli. Cook for 5 minutes, stirring occasionally, until broccoli is bright green and spinach is wilted.
Meanwhile, crack the eggs into a bowl and whisk with a fork. When the veggies are cooked, add the eggs to the pan, along with a pinch of salt and black pepper, and stir occasionally, until eggs are cooked through, about 3-4 minutes. Top with basil and red pepper flakes if using. Transfer to a plate to serve.
Meanwhile, toast a slice of your favorite gluten-free bread, and add sliced avocado on top, with a pinch of salt and/or red pepper flakes if desired.