I love the flavor of caramelized onions and they work perfectly as a filling for these French Onion Potstickers. Thinly sliced onions are seasoned with Worcestershire sauce, thyme, and beef broth, then cooked until deeply golden and caramelized. I added shredded mozzarella cheese to the cooled onions before wrapping them in wonton wrappers. Gruyere cheese would also be a great choice.
Be sure to serve the potstickers with the seasoned beef broth dipping sauce!
The potstickers can be made in advance. Once they are formed, place on a parchment lined baking sheet and freeze in a single layer. Once frozen, they can be transferred to a freezer bag. I doubled the recipe to make about 50 potstickers, so I had a freezer supply that lasted about a month.