Heat up the oil in a medium size pan on medium heat.
Add the onions and saute until it is a little brown. Next, add the chilli paste and mix them well. Let the chilli paste cook for 10 minutes with the lid on.
Add salt and brown sugar to the sambal and mix together. Let it cook for another 10 minutes to ensure that the chilli darkens.
Add water to the sambal and stir it well. Proceed to add the prawns to the sambal and stir them well. Make sure the prawns are well coated with sambal.
(Optional) For garnish, you can top it off with parsley leaves or coriander leaves.