Heat oil in a small Dutch oven over medium-high heat. Add onion, celery, carrot, and garlic to pan; sauté 8 minutes or until tender. Add broth, water, and tomatoes; bring to a boil. Stir in lentils; simmer 25 minutes, stirring occasionally. Stir in rice; simmer 20 minutes, stirring occasionally. Stir in red pepper, salt, and black pepper.