Prepare the chicken or pork intestines by thoroughly cleaning them and removing any excess fat or debris.
Cut the intestines into bite-sized pieces and thread them onto the bamboo skewers.
In a bowl, combine the soy sauce, vinegar, brown sugar, minced garlic, salt, and ground black pepper to create the marinade. Mix well until the sugar has dissolved.
Place the skewered intestines in a shallow dish, then pour the marinade over them, making sure they are evenly coated. Marinate the intestines in the refrigerator for at least 2 hours, or preferably overnight, to allow the flavors to penetrate.
Preheat a grill or charcoal barbecue to medium-high heat. Once the grill is hot, remove the skewered intestines from the marinade and place them on the grill grates.
Grill the isaw, turning occasionally, for about 10-15 minutes, until they are cooked through and slightly charred on the outside.
Remove the isaw from the grill and serve immediately with vinegar to dip.