Cut roast in half; place in 5 qt. slow cooker. Combine broth, apple juice, mustard; pour over roast. Cover and cook on low 4- 4½ hours or till meat is 160 degrees.
Remove roast and keep warm. For gravy, strain cooking juices and skim fat. Pour juices into a small saucepan. Combine cornstarch and water till smooth; gradually stir into juices. Bring to boil; cook and stir for 2 mins. or till thickened. Serve w/ pork.