Nam phrik kapi is probably the most well known nam phrik in Thailand. As the name suggests, it is made with kapi, a salted and fermented paste of fine shrimp known as khoei and is always served with fresh and/or parboiled vegetables, as well as egg-battered deep-fried vegetables, as described below. The amount of ingredients listed below for the nam phrik are largely for reference; a Thai chef would virtually never use measuring instruments to cook, and a dish is usually made to taste, keeping in mind a desired balance of the four tastes: sour, spicy, salty and sweet.
This is the typical Thai chile sauce that is found in many forms--served in restaurants, bottled, and made in homes. There are many variations, of which this is probably the most basic. It is served with almost every Thai appetizer and entree.
It may seem like cheating, but I like to use canned curry paste for this dish since it avoids the work of chopping and pounding that homemade curry paste involves. This dish takes its name from the northern Malaysian port city, but in Thailand the sauce is creamier and richer than the dry dark curries popular there.