In a medium-sized bowl whisk together the soy sauce, ¾ cup water, honey, rice vinegar, mirin rice wine, sesame oil, ginger, and garlic.
Add ½ cup of the teriyaki sauce mixture to a resealable plastic bag along with the cubed beef. Seal the bag and marinate the beef for at least 30 minutes or overnight in a refrigerator. Reserve the remaining 1 cup marinade for later and set aside.
If using wooden skewers, soak in water for 30 minutes before cooking.
Add the remaining teriyaki sauce mixture to a small saucepan, should be about 1 cup. Bring the teriyaki sauce to a boil over medium-high heat and cook for 1 minute.
In a small bowl mix together the cornstarch and 2 tablespoons of water to make a cornstarch slurry. Add the cornstarch slurry to the boiling sauce, and whisk to combine.
Continuously stir until a nice and thick sauce coats the back of a spoon, 30 to 60 seconds. Set the sauce aside.
Thread the marinated beef, pineapple wedges and red onion onto each skewer.
Heat the grill to medium-high. Add a small amount of vegetable oil on a folded piece of paper towel, and then carefully grease the grill with the oil. Once the grill is very hot, add the teriyaki beef skewers and discard the marinade.
Cook on one side uncovered for 3 minutes. Flip over and cook another 3 minutes. Cook on the remaining sides for 1 minute per side, or until the internal temperature of the beef reaches 130 degrees Fahrenheit for medium-rare, or 140 degrees Fahrenheit for medium.
Allow meat to rest for 5 minutes before serving.
Glaze skewers with teriyaki sauce and garnish with sesame seeds, green onions, and cilantro leaves. Serve extra teriyaki sauce on the side.