Arrange the carrots and onions in the bottom of your slow cooker.
Season the pork tenderloins with garlic powder, kosher salt and pepper.
Place the tenderloins on top of the carrots and onions.
Pour the sauce over the tenderloins.
Cover and cook on low for 3 hours or on high for 1 ½ hours or until a meat thermometer registers 145F.
Transfer the pork to a cutting board and let rest for 5 minutes. Then slice and arrange the sliced pork on a serving platter.
Meanwhile, using a slotted spoon, remove the carrots and onions from the slow cooker and arrange them on the serving platter.
Transfer the sauce from the slow cooker to a saucepot.
In a small bowl combine the cold water and cornstarch, stirring until the cornstarch is dissolved and blended.
Stir the cornstarch mixture into the sauce in the saucepot and bring to a boil over medium-high heat. Boil for at least I minute, stirring, until the sauce has thickened.
Drizzle some of the sauce over the pork and vegetables and sprinkle with sliced green onions. Serve any remaining sauce on the side.