Rice: Cook rice according to instructions on the package. Cover to keep warm when finished.
Veggies: Preheat oven to 400°F (204°C). In a medium bowl, toss together chopped sweet potato, drained chickpeas, oil, and spices. Spread onto a parchment-lined baking sheet. Cut red onion into large chunks and set them on the sheet. Bake for 30 minutes, flipping everything over after 15 minutes. Veggies are done when sweet potato is fork tender.
Sauce: Meanwhile, stir together all sauce ingredients, adding a splash of cold water to reach a pourable sauce consistency.
Collards: Sauté collard greens until soft (using this recipe - 20 minutes).
Assemble: Spoon cooked rice into serving bowls, followed by veggies, collards, and sauce!