Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Cut the seitan into bite-sized cubes and chop the broccoli into small florets and the bell pepper into thin strips.
Place the seitan, broccoli, and bell pepper on the baking sheet, then toss with olive oil, sea salt, black pepper, and garlic powder until evenly coated.
Roast the mixture for 20 minutes, flipping halfway through, until the vegetables are tender and the seitan is slightly browned and crisp.
While the vegetables roast, cook the quinoa in water or vegetable broth according to package directions and steam the shelled edamame until bright green.
In a small ramekin, whisk together the tahini and lemon juice, adding a teaspoon of warm water at a time until the sauce reaches a smooth, pourable consistency.
Assemble the power bowl by placing the cooked quinoa at the base and topping it with the roasted vegetable and seitan mixture and the steamed edamame.
Drizzle the lemon-tahini dressing over the entire bowl and enjoy immediately while warm.