In a medium stockpot, add chopped onion and carrots and sauté with some oil, on medium heat, until onions are soft and translucent. Stir occasionally. Add peeled and diced potatoes and sauté for a few more minutes, stirring occasionally.
Stir in green lentils, coconut milk, water, cumin, ginger, turmeric and vegetable stock cube, until combined.
Bring to a boil and simmer covered, until the lentils and potatoes are soft.
Add a pinch of cayenne pepper (optional), salt and black pepper to taste and top with red chili flakes for some heat (optional).