Preheat the oven to 425°F (220°C).
In a large bowl, combine acorn squash, red onion, carrots, yellow bell pepper, and chickpeas. Drizzle with olive oil, harissa, garlic powder, salt, and black pepper. Toss to coat evenly.
Transfer the coated chickpeas and vegetables to a large sheet and spread them out evenly.
Roast in the preheated oven for 15-17 minutes, or until the vegetables are tender and slightly caramelized. For more even roasting, consider tossing the vegetables once halfway through.
In the meantime, prepare the lemon yogurt sauce by mixing garlic powder, plain yogurt, lemon juice, and lemon zest in a small bowl. Set aside.
Once the vegetables and chickpeas are roasted, transfer them to a serving platter and top with a squeeze of lemon juice along with a garnish of fresh dill (optional).
Serve over cooked quinoa.