Halve, peel and finely dice your onion. Peel and finely chop your garlic.
Spoon out 2 tbsp of coconut milk into a bowl and set aside. Add the chopped onion and garlic to a pan with the coconut milk from the tin, 200ml boiling water and your stock cube (or use 200ml homemade stock). Simmer over a medium heat for 5 mins.
Finely chop the spinach and pile into the pan. Swirl through till just wilted. Immediately take off the heat and blend till smooth. Season with salt and pepper to taste. Dish up and garnish with a swirl of the reserved coconut milk.