Kapi is a salty fermented shrimp paste which is much loved in Thai cuisine. It is a dark purple, thick, soft paste, much thicker than the Chinese version. It has a very strong aroma and flavour which most farang find off-putting, but I love it.
Besides being an essential ingredient in Thai curry pastes, it can be added to stir fried water spinach. But most commonly it is made into a dip which is as ubiquitous in Thai homes as grilled cheese sandwiches are in North American ones. When I teach Thai cooking I usually include this in the class, just because it's so popular in Thailand; perhaps half the class likes it, and the rest can't even bring themselves to taste it, it smells so pungent.
Curious? Here's what you do:
Wrap a tablespoon or 2 of kapi in foil and toast in a dry frying pan for a minute or 2.
In a large mortar and pestle, grind together 1 or 2 garlic cloves and 1 or 2 fresh little hot Thai chilis. Grind to a paste.
Add the kapi and grind to combine.
Now add 1 or 2 tablespoons of fresh lime juice and fish sauce. I recommend using a spoon to mix this in, because if you splash yourself with this, you'll be discarding your shirt. Trust me.
That's it. Common dipping foods include fresh or steamed vegetables (greens, yard long green beans, snow peas, cucumber, eggplants) and steamed mackerel.