In order of pliability – from hardest to softest – pound the ingredients using a mortar and pestle and long handled spoon. Start with the rehydrated long red chillies, red birds eye chillies and salt until smooth and well combined.
Then incorporate all the other ingredients, one at a time, and pound until each ingredient is fully blended. Make sure they are combined before adding the next ingredient. Do this with everything except the shrimp paste, then pound until smooth, scraping down the contents with the spoon as you go.
Lastly add the shrimp paste and pound until it all looks like one pliable paste, then refrigerate to rest. After it has chilled, batch it up into portions and freeze what you won’t use quickly – putting your paste into a large holed ice cube tray is a great hack.