Stir together the short ribs and the reserved sauce, and season the mixture well with salt and pepper to taste.
Working with a few wonton wrappers at a time (keeping the others covered with plastic wrap), moisten the edges with water. Mound 1 scant tablespoon of the filling in the center of each wonton and press another wonton wrapper on top. Press out the air and press the edges very tightly to seal. Transfer to a flour-dusted sheet pan and cover with plastic wrap. Repeat with the remaining wonton wrappers and filling. (The ravioli may be frozen at this point and kept tightly wrapped in the freezer for up to 1 month. Freeze flat on a sheet pan and, when solid, transfer to an airtight container.)