In a large skillet, add onions and cook over medium-high heat (no oil needed). Make sure you keep an eye on it so it doesn't burn.
When onions are translucent (about 3 minutes), add peppers and cook another 2 minutes.
Add mushroom, broccoli, and corn, and mix well. Cook for 2 minutes before adding tomatoes, spinach and crushed red pepper flakes to taste. Cover with a lid and let the tomatoes cook down and corn defrost for 2 minutes.
Add hashbrowns and mix until all ingredients are together and cover again with lid. Every minute or so, flip over the sections of the hashbrowns to get a nice crispness. Cook hashbrowns for 3 minutes total.
Plate up hashbrowns and top with olives, avocado, nutritional yeast, and salsa or ketchup
Notes
**Since you're not using oil when cooking the vegetables. Feel free to add small amounts of water in order to stop sticking to the pan