Melt the butter in a saute pan over medium heat. Saute the chopped mushrooms with a pinch each of the salt and pepper until soft (5-8 minutes). Remove the mushrooms from heat and allow to cool.
Break the ground pork up into a large bowl, and combine with the ginger, soy sauce, sherry, sautéed mushrooms, and remaining salt and pepper. Fold in the diced purple cabbage. Chill for at least 10-15 minutes (or up to overnight).
First, set up your work station: On a clean flat surface (I like to use a cutting board), set out a small bowl of water and open your package of wonton wrappers. Lay a damp cloth over the package to keep the wrappers from drying out. Set the bowl of mushroom pork filling nearby.
Serve your simple pork & mushroom dumplings with a side of soy sauce for dipping, sprinkled with some chili flakes if you like a little heat.
Folding Dumpling Wrappers: There are so many types of dumpling shapes. For these, I folded the square wonton wrappers into a simple pleated shape. For step-by-step instructions on a few different shapes, check out Food52's excellent article on How to Make Dumplings Without a Recipe.