Scrape off the ginger skin with a spoon, peel the onions and garlic.
Mix the ginger, onions and garlic into a paste in a blender. If necessary, add a little coconut milk if it is too dry.
Put the turmeric, garam masala, chili powder, cumin, cayenne pepper and coriander in a bowl and mix together.
Heat 1 tablespoon of coconut oil (or other oil) in a large saucepan and sweat the paste in it for 2 minutes. Sprinkle in the spice mixture and fry while stirring.
Then add the vegetable stock, tomatoes and coconut milk and bring to the boil. Then cook the lentils for 30 minutes.