Heat the oil in a saucepan set over a medium heat and cook the onions, garlic and ginger for about 10 minutes until the onions are soft.
Meanwhile, use a sharp knife to shave the sweetcorn kernels off the cob (run the knife close to the cob to remove whole kernels). Add the sweetcorn kernels to the saucepan and cook for a few more minutes.
Remove half of the mixture from the pan and set aside. Add the stock and kohlrabi to the pan and simmer for about 10 minutes until the kohlrabi is soft. Stir in the coconut milk and simmer for a further 2 minutes. Using a hand blender (or in a food processor), blitz the mixture until smooth.
Return the sweetcorn and onion mix you set aside and stir back into the puréed soup in the pan. Season with salt and pepper to taste. Heat through.
Ladle the soup into bowls and add a sprinkle of paprika, an extra drizzle of oil, and some salt and pepper. Serve hot.