Defrost the coconut by leaving it in the fridge overnight or at room temperature
Finely chop the onions, tomatoes and green chilies
Add chillie flakes, black pepper and salt to the mortar, and grind to break up the whole peppers
Add the chopped onions and green chillies and grind them together
Add the tomatoes and grind them, mixing it with all the previously ground onions, chillies and spices
Finally, add the coconut to the mortar and mix all together
Take out the mixture from the mortar and add lemon juice to taste
To increase spiciness, add pepper and chillie powder to the coconut sambol