Put the pork tenderloin in the bottom of a slow cooker.
Pour in water, bouillon, and Worcestershire sauce into the slow cooker.
In a small bowl, stir together remaining ingredients. Sprinkle mixture over pork.
Cover slow cooker and cook on Low for 3 1/2 hours. {If possible, flip pork over after 2 1/2 hours.}
Place pork in separate container, cover tightly to keep warm.
Place a small amount of the liquid in a small container with a lid, pour the rest in a saucepan.
Mix the flour with the liquid in the small container and shake until well mixed. Add to saucepan and stir while heating, being sure to mix well and breaking up any lumps. Heat until thickened to your liking, stirring constantly.
Or, if you’re brave, you can add all of the liquid to the pan, and add the flour gradually and directly to it, whisking vigorously and constantly while heating to ensure flour is evenly distributed.
Add the roast back to the gravy.
Serve pork with the gravy – especially good over smashed potatoes.