MIX together vinegar, lemon juice, garlic powder, salt, pepper and olive oil in a small bowl until well combined. Place beef, vegetables, pineapple and marinade in a gallon-sized resealable plastic bag. Marinate in refrigerator 5 hours or overnight.
SPRAY grill grate or broiler pan with no-stick cooking spray. Heat grill or broiler. Thread meat onto skewers alternating with vegetables and pineapple. Season generously with salt and pepper.
BROILER: Place kabobs about 5 inches from broiler element. Broil 5 to 8 minutes, turning once, until meat is well browned and cooked to desired doneness.
GAS GRILL: Grill kabobs 8 minutes for medium-rare or 9 minutes for medium, or to desired doneness.