In a medium saucepan, combine rice and 2 cups of water. Bring to a boil, cover, and reduce heat to low; simmer for 30-40 minutes until done. Meanwhile, in a medium skillet, sauté onion and garlic in olive oil until translucent, 3-4 minutes. Add black beans, water, cumin, and chili powder. Simmer until rice is done. Mash some of the beans to thicken if desired. Top with salsa and cheese, if desired.