1 cup soy sauce
1/2 cup brown sugar
3 tablespoons cider vinegar
3 cloves minced garlic
2 teaspoons grated fresh ginger or 1 teaspoon ground ginger
2 pounds beef sirloin steak, cut into 1-1/4-inch cubes
1 large green pepper, cut into 1-1/2-inch pieces
1 large onion, cut into wedges (optional)
2 cups fresh pineapple chunks
In a large bowl whisk together first 5 ingredients. Pour a little more than half the marinade into a large re-sealable plastic bag. Add beef. Seal bag and turn to coat. Refrigerate for up to 8 hours. Cover and refrigerate reserved marinade.
Remove beef from the marinade. Alternate beef, peppers, onions, and pineapple on metal or soaked wood skewers. Grill kabobs uncovered, over medium heat for about 5 minutes on each side or until steak is done to your liking. Baste skewers with reserved marinade the last few minutes of grilling.