Roast the Veggies: Preheat the oven to 450°F. Add the veggies to a large baking sheet, add 2tbsp olive oil, chili powder, salt & pepper. Mix well and spread evenly on the baking sheet. Bake for 30~35 minutes or until the veggies are tender and lightly browned around the edges.
Make the Tomato-Chipotle Sauce: Blend chipotle and garlic until smooth. Add the tomatoes and pulse until coarsely chopped. Heat 1tbsp oil in a saucepan, add onions and cook for 5~7 minutes or until soft and lightly browned around the edges. Add the tomato sauce and cook for 5~6 minutes or until the sauce thickens.
To Serve: Spread rice in a casserole dish and top with the roasted vegetables followed by the tomato-chipotle sauce. Garnish with chopped red onion and sour cream, if desired.