Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Place the broccoli florets and sliced bell peppers on the sheet, drizzling with half the olive oil and seasoning with sea salt and black pepper.
Roast the vegetables for 18-20 minutes, tossing halfway through, until they are tender and have developed caramelized edges.
While the vegetables roast, press the extra firm tofu between paper towels for 10 minutes to remove excess water, then slice into 1-inch cubes.
In a shallow bowl, combine the nutritional yeast and garlic powder, then toss the tofu cubes until they are thoroughly coated.
Heat the remaining olive oil in a large non-stick skillet over medium-high heat and sear the tofu for 3-4 minutes per side until golden.
Pour the tamari over the tofu during the last minute of cooking, tossing quickly to glaze the cubes, then serve immediately with the roasted vegetables.