Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Drain the firm tofu and press it between paper towels to remove excess moisture, then cut it into 1-inch cubes.
In a large bowl, combine the tofu cubes, chickpeas, broccoli florets, and cauliflower florets.
Drizzle with olive oil and sprinkle with garlic powder, sea salt, and black pepper, tossing until everything is evenly coated.
Spread the mixture in a single layer on the baking sheet and roast for 25 to 30 minutes, tossing halfway through, until the vegetables are tender and the tofu is golden.
In a small jar, whisk together the tahini, lemon juice, and a teaspoon of warm water until smooth.
Transfer the roasted mixture to a bowl, sprinkle with nutritional yeast and hemp hearts, and finish with the tahini drizzle.