Cook rice in 2 cups of the water as directed on package. Stir bouillon cubes into remaining 1 cup water. In small bowl, stir together cornstarch and 2 tablespoons of the bouillon mixture until well blended; set aside.
Meanwhile, in 10-inch skillet, heat oil over medium-high heat. Add onion; cook and stir 2 minutes. Add green beans, garlic and remaining bouillon mixture; cover and cook 5 minutes.
Add zucchini and squash medley; cook 2 to 3 minutes, stirring occasionally, until vegetables are crisp-tender. Stir in cornstarch mixture; cook and stir until mixture is bubbly and slightly thickened.
Add basil and butter beans; cook 1 to 3 minutes, stirring occasionally, until thoroughly heated. Season to taste with salt and pepper. Serve over rice. If desired, garnish with additional basil sprigs.