Toast the peanuts over low heat with a small amount of oil, stirring constantly to ensure even toasting. Once they begin to turn a deeper color and develop a few scattered charred spots, remove them from the pan.

Coarsely crush the peanuts using a food processor.

Remove the seeds and pith from the red chilies, then cut them into short pieces. Cut the onion, garlic, galangal, and lemongrass into small pieces.

Blend the red chilies, onion, garlic, lemongrass, galangal, belacan, and vegetable oil until smooth.

Transfer the mixture to a pan and sauté over low heat for a few minutes, or until most of the moisture has evaporated.

Add the ground peanuts to the chili paste. Pour in some water, then add the asam keping, sugar, and salt. Simmer for a few minutes—the peanut sauce will gradually thicken. Stop cooking once it reaches your preferred consistency. The peanut sauce is ready.

Cut the chicken breast into small bite-sized pieces (about 2 × 2 cm).

Cut the onion, garlic, galangal, and lemongrass into small pieces. Add the onion, garlic, galangal, lemongrass, belacan, and vegetable oil into a blender and blend until smooth. Add a splash of water if necessary to help it blend.

Combine the chicken with the blended paste, then add turmeric powder, sugar, ground white pepper, coriander powder, fennel powder, cumin powder, kicap manis, and salt. Cover and refrigerate for at least 4 hours, or overnight for the best flavor.

Thread 4–5 pieces of marinated meat onto each bamboo skewer. Press them lightly so they sit flat, which helps the chicken cook evenly on the grill.

Preheat a grill or grill pan until very hot. Lightly grease the surface with oil, then place the bamboo skewers on the hot grill. Grill over medium heat for about 2–3 minutes on each side.

Brush the chicken with more oil while grilling to keep it moist. Continue grilling until the meat is golden brown and the edges are lightly charred.

Serve immediately with satay sauce, cucumber slices, red onion wedges, and ketupat.