In a medium saucepan, combine the pineapple juice, soy sauce, brown sugar, ginger and garlic powder. Stir and bring to a simmer. Combine the cornstarch and cold water in a separate bowl. Whisk the cornstarch mixture into the simmering soy sauce mixture. Continue to simmer and stir until thickened. Remove from heat, cover and set aside to cool.
MARINATE:
Put the butterflied pork in a large zip baggie, and add half of the teriyaki sauce to the bag. Rub the bag to coat the pork with the sauce; refrigerate for at least one hour to marinate. You can refrigerate for a few hours, if you'd like. Cover the rest of the teriyaki sauce and save for later.
GRILL:
Preheat your grill to medium high heat. Place the vegetables on a baking sheet, drizzle with olive oil and sprinkle with salt and pepper. Grill the pork and vegetables until done. Chop the pork and vegetables into small chunks.
ASSEMBLE NOODLE BOWLS:
Toss hot noodles with teriyaki sauce. Divide the noodles between four bowls. Divide the pork and vegetables between the four bowls. Sprinkle with sesame seeds, for garnish.
Notes
*Time Saver Tip: Use store bought teriyaki sauce to toss with your noodles instead of making the homemade. You can also buy *fresh* udon noodles- they'll have a quicker cooking time.