Preheat your oven to 400°F and line a baking sheet with parchment paper.
Toss the diced red bell pepper, zucchini, and red onion with half of the olive oil and a pinch of sea salt.
Spread the vegetables on the baking sheet and roast for 20 minutes until they are tender and slightly caramelized.
Season the chicken breast with salt and pepper, then grill over medium-high heat for approximately 6 minutes per side until the internal temperature reaches 165°F.
While the chicken and vegetables cook, prepare the quinoa according to the package directions.
In a small bowl, whisk together the tahini, lemon juice, and a tablespoon of warm water until the dressing is smooth and pourable.
Slice the grilled chicken into thin strips.
Assemble your power bowl by placing the cooked quinoa at the base and topping it with the roasted vegetables and grilled chicken.
Finish the dish by adding fresh avocado slices and drizzling the creamy lemon tahini over the top.