Preheat your oven to 425°F and line a large baking sheet with parchment paper.
Place the riced cauliflower in a clean kitchen towel and squeeze forcefully to remove as much liquid as possible until the cauliflower is very dry.
In a large mixing bowl, combine the dried cauliflower, ground flaxseed, almond flour, pea protein powder, nutritional yeast, oregano, garlic powder, and sea salt.
Mix the ingredients thoroughly to form a dough, then press it into a thin, even circle on the prepared baking sheet.
Bake the crust for 18 to 20 minutes until the edges are golden brown and the center feels firm to the touch.
While the crust bakes, toss the sliced bell pepper, zucchini, and red onion with olive oil and roast on a separate tray for 10 minutes.
Spread the tomato sauce over the baked crust, top with the roasted vegetables, and return to the oven for an additional 5 minutes.