Heat olive oil in a large skillet over medium heat. Add garlic and onion, and cook, stirring frequently, until onions have become translucent, about 2-3 minutes. Stir in rice until toasted, about 2 minutes.
Stir in tomato sauce and vegetable broth, and bring to a simmer, about 2 minutes. Stir in corn, carrots, peas, chili powder and cumin; season with salt and pepper, to taste. Bring to a boil; cover, reduce heat and simmer until rice is cooked through, about 13-16 minutes. Stir in tomatoes.