Preheat the oven to 400°F and line a large baking sheet with parchment paper.
Slice the seitan into bite-sized cubes and chop the red bell pepper into one-inch pieces.
In a large bowl, toss the seitan, broccoli florets, chopped bell pepper, and chickpeas with avocado oil, sea salt, black pepper, garlic powder, and smoked paprika until evenly coated.
Spread the seasoned mixture in a single layer on the prepared baking sheet and roast for 20 minutes, or until the vegetables are tender and the seitan is slightly crisp.
While the vegetables roast, whisk together the tahini, lemon juice, maple syrup, and water in a small bowl until the dressing is smooth and creamy.
Assemble the bowl by placing the warm cooked quinoa at the base, topping with the roasted seitan and vegetable mixture, and drizzling the lemon-tahini dressing generously over the top.