Shrimp Paste

Kapi is the hidden ingredient in Thai cooking. You rarely taste it directly, but take it out of a curry paste and the curry tastes thin and flat. It is a dense, purple-grey paste of fermented shrimp, and a teaspoon of it goes a long way.

How it is made

Tiny shrimp or krill (kuey) are mixed with salt, sun-dried on mats, ground, and packed into containers to ferment for weeks or months. The process is repeated until the paste is smooth and dense. Coastal towns such as Klong Khon in Samut Songkhram and Rayong are famous for their kapi, and the best is soft, aromatic and a deep purplish colour.

How to cook with it

In curry pastes, it is pounded in at the end with the other ingredients, usually half a teaspoon to a teaspoon per batch of paste. When the paste is fried in coconut cream, the kapi cooks out and becomes a rich, savoury base.

In nam prik kapi, the most traditional of all Thai chilli dips, it is the star: pounded with garlic, bird’s eye chillies, palm sugar, lime juice and pea eggplants, and eaten with fried mackerel (pla tu), omelette and a basket of raw and blanched vegetables.

It also seasons khao kluk kapi, rice fried with shrimp paste and served with sweet pork, green mango, shallots and omelette, and southern sour curries like gaeng som.

Toasting kapi

Many cooks toast kapi before using it. Wrap a teaspoon in foil or banana leaf and toast it in a dry pan for a minute or two on each side, until fragrant. This deepens the flavour and takes the raw edge off the smell. Open a window: it is pungent while it toasts.

Buying and storing

Thai kapi is sold in small plastic tubs or glass jars in Asian grocers; it is softer and more aromatic than the dry blocks used in Malaysian (belacan) or Indonesian (terasi) cooking, though those can be used. Keep it tightly sealed in the fridge, ideally inside a second container or zip bag to contain the smell. It keeps for many months.

Substitutes

For a non-vegetarian substitute, use an extra splash of fish sauce or a mashed anchovy fillet. For vegetarian curry pastes, use a teaspoon of fermented soybean paste (tao jiew), white miso or Korean doenjang, with a little extra salt.

Cook’s tip

If you are making curry paste for the first time and are nervous about the smell, start with half a teaspoon. You will not taste shrimp in the finished curry, only a rounder, deeper sauce.