Cook the quinoa: In a medium saucepan, combine the quinoa, water or chicken broth, olive oil, and salt (if using water). Bring to a boil over medium-high heat. Reduce heat to low, cover, and simmer for 20 minutes, or until all the liquid is absorbed. Remove from heat and let sit, covered, for 5 minutes. Fluff with a fork and set aside.
Roast the veggies: Preheat your oven to 400°F (204°C). Add the diced potato, sweet potatoes, broccoli florets, and red onion slices to a large bowl. Drizzle with olive oil, then season with salt, pepper, garlic powder, oregano, and paprika. Toss until evenly coated. Spread the veggies in a single layer on a large baking sheet (use two if needed to avoid overcrowding). Roast for 30–35 minutes, tossing halfway through, until tender and golden brown with crispy edges. When the veggies have about 5-10 minutes left, sprinkle the parmesan on top.
Air fry the chickpeas. Pat the chickpeas dry with a towel. Toss with olive oil, salt, cumin, garlic powder, paprika, and cayenne until well coated. Air fry at 380°F for 15 minutes, shaking the basket every 5 minutes, until crispy.
Make the green tahini sauce: In a food processor or blender, combine garlic cloves, tahini, olive oil, lemon juice, lemon zest, cumin, salt and parsley. Blend until smooth. Slowly add ice water, 1 tablespoon at a time, until the sauce reaches a pourable consistency. Taste and adjust seasoning if needed with more salt.
Assemble the bowls: Divide the cooked quinoa between four bowls. Top each with a generous portion of roasted veggies. Drizzle with garlic tahini sauce and enjoy.