The traditional way to mix this sauce is by mortar and pestal but, feel free to use a blender. Tho try to leave some visible chunks in your sauce.
Add your cans of seafood stock to your blender. Obviously the more you thin this sauce, the further she'll go. :0)
There are several different types of Nam Prik depending on the Thailand region. Some are solid - some are thin. This type of Prik is meant to be thin enough to allow its juices to seep into a sticky rice based dish. And, chunky enough to seat itself on the top.