Combine the hoisin, green onions, soy sauce, rice wine vinegar, and garlic in a large zip-top bag. Add the pork to the bag, seal and let it marinate for at least two hours or overnight, turning the bag occasionally.
1/2 cup hoisin sauce, 1/4 cup sliced green onions, 1/4 cup low-sodium soy sauce, 2 tbsps. rice wine vinegar, 3 cloves garlic, minced, 2 (1 lb.) pork tenderloins, trimmed, silverskin removed*