In a medium-sized pot, sauté onions until golden brown. Add carrots and celery; sauté for 5 minutes. Add lentils, water, salt, pepper, cumin powder, coriander and cardamom; on high heat, bring to a boil, lower heat and leave to simmer for 20 minutes.
Puree the ingredients with a hand blender until the soup has a smooth texture and leave it to simmer on low heat for 5 minutes.
To serve, add a generous scoop of cooked rice in a bowl. Ladle the warm, flavourful lentil soup over the rice and a generous serving of simple green salad. For an extra kick of flavour, add a sprinkle of chilli powder and a squeeze of lemon juice. This well-rounded meal balances warmth, spice, and freshness, creating a delightful dining experience.