Preheat oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Pat the chicken breast dry and cut into 1-inch bite-sized pieces.
In a large bowl, combine the chicken, chickpeas, broccoli florets, and sliced bell peppers.
Drizzle with olive oil and sprinkle with sea salt, black pepper, garlic powder, and smoked paprika.
Toss everything until evenly coated, then spread in a single layer on the prepared baking sheet.
Roast for 18-20 minutes, or until the chicken is cooked through and the vegetables are tender and slightly charred.
While roasting, whisk together the tahini, lemon juice, dried oregano, and water in a small bowl until the sauce is smooth and pourable.
Divide the roasted mixture into bowls and drizzle the zesty tahini sauce over the top before serving.