Whisk together the brown sugar, soy sauce, pineapple juice, water, vegetable oil, ginger and garlic in a large bowl.
1½ cups light brown sugar, 1 cup soy sauce, ½ cup pineapple juice, ½ cup water, ¼ cup vegetable oil, 1 tablespoon ginger, 3 cloves garlic
In a resealable container, add the vegetables and ½ cup of the marinade mixture. Toss to coat. Refrigerate until ready to assemble the kabobs.
2 large green bell peppers, 1 sweet onion
Add the beef cubes to the remaining marinade and toss to coat. Cover bowl with plastic wrap. Marinate beef in refrigerator for 4-24 hours. (The longer it marinates, the more flavorful it will be).
4 pounds boneless round steak
Remove beef from the marinade, shaking to remove any excess liquid. Discard marinade. Repeat with the vegetables.
Thread the meat and vegetables onto the skewers. Lightly salt and pepper if desired.
bamboo or metal skewers
Preheat grill for medium heat and lightly oil the grate. Cook the kabobs on preheated grill until the beef is cooked through, about 3 minutes per side to cook evenly.
Remove from the heat and let rest 5 minutes before serving.