Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Cut the tempeh into half-inch cubes and chop the broccoli and bell pepper into uniform pieces.
In a large mixing bowl, whisk together the tamari, olive oil, garlic powder, sea salt, and black pepper.
Add the tempeh, broccoli, and bell pepper to the bowl, tossing thoroughly until every piece is coated in the marinade.
Spread the mixture in a single layer on the prepared baking sheet, ensuring enough space for even roasting.
Bake for 20 to 25 minutes, tossing halfway through, until the tempeh is golden and the vegetables are tender.
Remove from the oven and immediately sprinkle the nutritional yeast over the hot mixture to help it adhere.
Place the warm cooked quinoa in a bowl and top with the roasted tempeh and vegetable medley.