Pound the galangal, lemongrass, turmeric, coriander seeds and roasted cumin powder in a mortar. Add some coconut milk and mix well.
Add salt, the rest of the coconut milk, and the sweetened condensed milk, and stir. Marinate the pork in the mixture for 30 minutes before putting the pieces on the skewers.
Grill over medium fire. Sprinkle the coconut milk over the skewered pork while it’s cooking.