Finely cut up the dried red chili peppers with a pair of kitchen scissors.
Cut them into thin pieces at an angle as shown. Your hands may burn from the oil coating the surface of the peppers, so I recommend wearing gloves; watch TV while cutting, since it takes a bit of time.
Remove as many seeds as possible. With your hand covered in a plastic bag, rub the cut peppers together to release the seeds; they'll filter through the colander.
I filtered this many seeds with 150 g of red chili peppers (about 2/3 cup).
Rinse the cut peppers, then soak them in water for about 1/2 day, refreshing the water twice. When draining, there will be fine bits to discard, so drain slowly to separate them out.
These are bawang merah onions. They can also be found as "hom daeng," the Thai word for shallots. They can be bought online, but since (I suspect) they're expensive, you can substitute with regular onions.
This is belacan, a dried paste made from baby shrimp. If you don't have any, you should be able to substitute with the Thai condiment "kapi" or with Japanese "ami no shiokara" (fermented krill).
Place all of the ingredients in a food processor or blender and blend into a smooth paste. It's done!
Transfer the sambal to a Tupperware or resealable container, and store it in your refrigerator; it can keep for about 6 months if stored in the chilled compartment. You could also divide it into smaller portions and freeze them.
You can't eat this sambal as is, it needs to be used in cooking, not as a finishing sauce so be careful. For the type of sambal that can be eaten as is, refer to Recipe ID: 821573.
Story Behind this Recipe
This is a condiment that we always keep in the refrigerator at my house.
Any remaining seeds will result in a poor texture, and will make the sambal very spicy. Be sure to carefully filter them out. Switching the food processor or blender on and off should help the ingredients blend more quickly. You can use the soaking water on the plants in your garden as an effective insect repellent.