Place the onions and carrots in a large, heavy-bottom saucepan with the oil.
Cover and cook over low heat, stirring occasionally, until the onions are translucent.
Add the water, lentils, tomatoes, corn, and sweet potatoes.
Bring to a boil, then reduce heat, cover, and simmer for 25 minutes.
Add the tamari, rice, and parsley and heat through before serving.