Heat oil in a large deep saucepan over medium heat. Add onion, celery, carrot and garlic. Cook for 8 minutes or until softened. Stir in curry paste and cook for 1 minute or until aromatic.
Add lentils, stock and 3 cups water. Bring to the boil, reduce heat and simmer for 35 minutes or until lentils are tender. Add cabbage and cook for 3 minutes or until wilted. Season with salt and pepper. Ladle into bowls and top with coriander. Serve with chapattis.