Peel the yellow eggplants, collect the seeds, and soak the flesh in salted water.
Measure the amount of fermented shrimp paste (kapi), garlic and palm sugar following the ratios of a basic chili relish recipe (น้ำพริกกะปิมาตรฐาน). Arrange the ingredients next to each other so you can visualize their proportions.
Begin preparing the relish in a mortar and pestle the same way you would a basic chili relish – start by pounding the garlic with the kapi and add dried shrimp powder.
Taste and season with salt and fish sauce. Once you are satisfied with the saltiness of the relish, add the palm sugar at the ratio indicated. Season to a sweet-salty flavor profile.
Season with to a sour leading flavor profile using lime juice and green mandarin orange juice (น้ำส้มเหม็น).
Add the chilies. Bruise them using the pestle to release the desired spiciness.
If used, mix in the sweet-sour fruits: the salacca (สละ หรือ ระกำ) and hairy-fruited eggplant (มะอึก).
Add a generous amount of the yellow eggplant seeds.