Step 1

In a shallow dish, mix together 3 tablespoons soy sauce, olive oil, 1 clove minced garlic, red pepper flakes, salt, and pepper. Add pork cubes, and turn to coat evenly with marinade. Cover, and refrigerate for 3 hours.

Step 2

In a saucepan, combine beef broth, cornstarch, 2 tablespoons soy sauce, brown sugar, 2 cloves minced garlic, and ginger. Bring to a boil, stirring constantly. Reduce heat, and simmer 5 minutes.

Step 3

Preheat an outdoor grill for high heat and lightly oil grate. Thread pork cubes onto skewers, alternating with mushrooms, onion, tomatoes, and pineapple chunks.

Step 4

Cook on grill for 15 minutes, or until meat is cooked through. Turn skewers, and baste often with sauce during cooking.