In a nonstick skillet over medium-high heat, sauté onion in a bit of oil or water for 2-3 minutes. Toss in bell peppers and sauté for another minute or so.
Crumble tofu into pan. Stir in onion and garlic powder and nutritional yeast. Pan-fry, stirring often, until excess water has cooked out of the tofu.
Stir in fresh spinach and cook until just wilted. Sprinkle on optional vegan cheese, reduce heat to low and allow to melt.
Top with black salt and pepper to taste. (I prefer adding black salt at the end because it retains more of its unique "eggy" smell when it isn't cooked.)