1.Mix Cornstarch, Broth, Water, Soy, Sugar, Garlic And Ginger In Saucepan. Cook And Stir Until Mixture Boils And Thickens. 2.Thread Alternately Beef, Mushrooms And Onions On 4 Long Skewers. 3.Grill Kabobs 20 Min. Or Until Done, Turning And Brushing Often With Broth Mixture. Place 1 Tomato On End Of Each Skewer. 4.Heat Remaining Broth Mixture To A Boil. Serve With Kabobs And Rice.