Put the lemon grass, ginger, chillis, garlic, lime juice, water, coriander and soy sauce in to a blender and blend until it is a paste.
Put the chicken breast in a food processor and blend until it is ground in to a mince. Put in a bowl with half of the paste mixture and mix well. Roll in to 16 meatballs and put on a baking tray and put in the oven at 190C for 25 minutes.
Heat a little oil in a pan and add the shallots and the rest of the paste and cook for 1-2 minutes. Add the coconut milk, chopped tomatoes and the cooked meatballs and gently simmer for 10 minutes before serving.