Trim fat from meat. Butterfly meat by cutting each tenderloin in half horizontally, cutting to within 1/2 inch of the opposite side. Spread open. Place meat between two sheets of plastic wrap. Using the flat side of a meat mallet, pound meat lightly until about 1/4 inch thick. Remove plastic wrap. Spread meat with mustard.
For filling, in a medium bowl combine stuffing mix and ham. Drizzle with broth, tossing to moisten. Spread filling over meat. Starting from a long side, roll up each tenderloin into a spiral. Tie at 2-inch intervals with 100% cotton kitchen string.
Wrap each tenderloin in plastic wrap. Place in a freezer bag or container; seal and freeze for up to 1 month.
To serve, thaw in the refrigerator overnight (centers may still be a little icy). Preheat oven to 425 degrees F. Unwrap tenderloins. In a small bowl combine egg and the water; brush over meat. Spread crushed crackers on waxed paper; roll meat in crackers to coat. Place on a foil-lined baking sheet.