Preheat the oven to 425 degrees F.
Line two large sheet pans with parchment paper.
Add the sweet potato, cauliflower, red onion, and red bell pepper to one sheet pan.
Toss those vegetables with 2 tablespoons olive oil.
Season them with the kosher salt, garlic powder, smoked paprika, cumin, and black pepper.
Spread the vegetables into an even layer with space between the pieces.
Add the zucchini and chickpeas to the second sheet pan.
Toss the zucchini and chickpeas with the remaining 1 tablespoon olive oil.
Spread them into an even layer with space between the pieces.
Roast the sweet potato, cauliflower, red onion, and red bell pepper for 25 to 30 minutes.
Add the zucchini and chickpea pan during the final 18 to 22 minutes of roasting.
Stir the vegetables once while they roast.
Let the vegetables roast until the edges are browned and the centers are tender.
Warm the cooked rice, quinoa, farro, or couscous while the vegetables finish roasting.
Whisk the tahini, lemon juice, warm water, olive oil, maple syrup, grated garlic, kosher salt, and black pepper together.
Add more warm water, one teaspoon at a time, if the sauce is too thick.
Place the warm grain in the bottom of each bowl.
Add the baby spinach or chopped romaine.
Top with the roasted vegetables and chickpeas.
Add the feta, goat cheese, or dairy-free cheese.
Sprinkle with toasted pumpkin seeds or sliced almonds.
Add fresh herbs and lemon wedges.
Drizzle with the creamy lemon tahini sauce.
Serve right away.