Cut the pork tenderloin into cubes.

Grate the onion and crush the garlic.

Combine the grated onion, crushed garlic, sweet soy sauce (ketjap manis), salt, white pepper, ground coriander, ground cumin, lemon juice, and sambal oelek (if using) in a bowl to make the marinade.

Add the pork cubes to the marinade and ensure they are well coated.

Let the meat marinate for at least 30 minutes in the refrigerator.

If using wooden skewers, soak them in water for 30 minutes to prevent burning.

Thread the marinated pork cubes onto the skewers.

Preheat a grill or grill pan to medium-high heat.

Grill the skewers for approximately 10 minutes, or until the pork is cooked through and slightly charred.

Baste the skewers with the remaining marinade during the grilling process.

Serve the sate immediately.