Prik nam pla is a sauce that Thai people use as the all-purpose flavour enhancer. It is a tableside condiment you put on the finished dish, much like salt and pepper in the West, but it's not something you cook with. Prik nam pla is salty, spicy, umami and acidic. When your Thai food feels like it's not quite perfect - perhaps a little flat - these are the flavours that are usually missing. This is why it works in so many situations. Prik nam pla straight up is quite intense, and a little goes a long way. If you want to be able to use it more liberally, add a splash of water to dilute and a touch of sugar to help balance the salt and the acid. Prik nam pla will keep indefinitely in the fridge because it's so salty. However, the flavour deteriorates so not too long. -The amount of lime juice to add it totally up to you. I like it heavier on the lime which I find makes it less salty and more versatile, so I use a general ratio of 3 parts fish sauce to 1 part lime juice.-