1. Heat oil in a large pan over medium heat.
2. Add onions, celery, and carrots. Cook for five minutes or until the onions are soft and translucent, stirring frequently.
3. Add garlic and curry powder and cook for another minute.
4. Add lentils, stock, and tomato juice.
5. Bring to a boil, then lower heat, cover, and simmer for 25 minutes or until the vegetables are tender. Season to taste with salt and pepper.