Whisk together hoisin sauce, 2 tsp. rice vinegar, soy sauce, cornstarch, and 1/2 cup water in small bowl. Set aside.Heat skillet or wok over medium heat. Add oil, then ginger and garlic. Stir-fry 1 to 2 minutes, or until garlic turns pale gold.Add tempeh and hoisin sauce mixture to pan. Stir to coat tempeh. Cover, reduce heat to medium-low, and simmer 2 minutes, or until sauce begins to thicken.Stir in green beans. Cover, and simmer 4 to 5 minutes, or until beans are hot, stirring occasionally. Stir in remaining 1/2 tsp. rice vinegar. Serve topped with cashews.