Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Drain the tofu and press it firmly between paper towels to remove as much moisture as possible, then cut into 1-inch cubes.
In a large bowl, toss the tofu cubes, broccoli florets, and cauliflower florets with the olive oil, sea salt, black pepper, and garlic powder until evenly coated.
Spread the tofu and vegetables in a single layer on the prepared baking sheet.
Roast for 25 to 30 minutes, tossing halfway through, until the vegetables are tender and the tofu edges are crisp and golden.
While the vegetables roast, prepare the dressing by whisking together the tahini, lemon juice, and water in a small bowl until smooth and pourable.
Thaw the edamame by steaming briefly or rinsing under hot water, then drain well.
Assemble the bowl by placing the cooked quinoa at the base and topping it with the roasted tofu, broccoli, cauliflower, and edamame.
Drizzle the creamy tahini dressing over the top and serve immediately.