Stir the stock, cornstarch, garlic, brown sugar, ketchup and vinegar in a 2-quart saucepan. Cook and stir over medium-high heat until the mixture boils and thickens. Remove the saucepan from the heat.
Thread alternately the pork, mushrooms and onion onto 4 skewers.
Lightly oil the grill rack and heat the grill to medium. Grill the kabobs for 20 minutes or until the pork is cooked through, turning and brushing often with the stock mixture. Place 1 tomato onto the end of each skewer.
Heat the remaining stock mixture over medium heat to a boil. Serve the stock mixture with the kabobs and rice.
Note: Swanson® Seasoned Chicken Broth with Roasted Garlic is no longer available. Campbell's Kitchen has modified this recipe with chicken stoc k to deliver the same great dish you enjoyed.
Serving Suggestion: Serve with grilled corn-on-the-cob and a tossed green salad. For dessert serve sliced watermelon.