Heat oil in a heavy-based saucepan over medium heat
2 tsp olive oil
Add carrot, sweet potato, onion, and celery and cook for 5 minutes, or until vegetables are soft
1 carrot, 1 onion, 2 sticks celery, 1 sweet potato
Add garlic, ginger, lentils and spices, and stir to combine
1 clove garlic, 1 tbsp ginger, 1 cup dried red lentils, 2 tsp garam masala, 1/2 tsp chilli powder
Add tomatoes and water and bring to the boil
1 can tomatoes, 1 l water
Reduce heat and simmer for 30 minutes, or until lentils are soft
If soup tastes too acidic, add sugar
1 tbsp sugar
Season with pepper
black pepper
Spoon into bowls and serve with a spoonful of yoghurt on top
1/3 cup reduced-fat natural yoghurt