This recipe was adapted from MMMMMaimi by Carol Kotkin and Kathy Martin.
Soak wooden skewers in cold water for about 30 minutes.
Combine all the ingredients in a blender or food processor. Process until smooth, scraping down the sides of the blender once or twice. Use immediately or refrigerate for up to 2 weeks.
Rinse the pork, pat dry with paper towels. Place the pork in a non-reactive container and add the marinade. Refrigerate overnight, turning several times to distribute the marinade.
Remove the pork from the refrigerator 1 hour before grilling. Skewer 5 pieces of pork onto each stick. Grill the pork and occasionally baste with the reserved marinade. Cook until brown on all sides (about 15 minutes). Serve on a platter garnished with onion slices and cilantro sprigs.
Serves 8 to 10.