Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Drain and rinse the chickpeas, then pat them very dry with a clean kitchen towel to ensure they crisp up in the oven.
Cut the chicken breast into bite-sized cubes and slice the red bell pepper into thin strips.
Place the chicken, chickpeas, broccoli florets, and bell pepper onto the prepared baking sheet.
Drizzle with olive oil and sprinkle with sea salt, black pepper, garlic powder, and smoked paprika.
Toss everything thoroughly to ensure an even coating of oil and spices, then spread into a single layer.
Roast for 20 to 25 minutes, tossing halfway through, until the chicken is cooked through and the chickpeas are golden and crunchy.
While the tray roasts, whisk together the Greek yogurt, lemon juice, and tahini in a small bowl until smooth.
Transfer the roasted chicken and vegetables to a serving bowl and drizzle the creamy lemon-tahini sauce over the top.