Preheat your oven to 425°F (220°C). Line a large sheet pan with parchment paper for easy cleanup.
In a large bowl, combine sweet potato cubes, chickpeas, broccoli florets, and red onion wedges. Drizzle with 2 tablespoons of olive oil, then sprinkle with smoked paprika, cumin, garlic powder, salt, and pepper. Toss well to coat evenly.
Spread the seasoned mixture in a single layer on the prepared sheet pan. Roast for 25-30 minutes, stirring halfway through, until sweet potatoes are tender and chickpeas are golden and crispy.
While the vegetables roast, divide the cooked rice and mixed greens among four serving bowls.
Once roasted, remove the sheet pan from the oven. Spoon the roasted vegetables and chickpeas over the rice and greens. Top each bowl with a generous dollop of hummus and a squeeze of lemon juice if desired. Serve immediately.