In a medium bowl, combine corned beef, onion, bell pepper, celery, pickles, Swiss cheese, mayonnaise, garlic powder, onion powder, black pepper and Worcestershire sauce. Mix until all ingredients are thoroughly combined.
Brush melted butter on a baking sheet.
Place a wonton wrapper on the baking sheet. Put 1 tablespoon of the corned beef mixture in the center of the wrapper.
Fold the wrapper in half to form a triangle and press the edges together to seal.
Brush the top of the triangle with melted butter.
Repeat with remaining wrappers and filling.
Bake for 12-15 minutes, until golden brown.
Serve with mustard and horseradish for dipping.
Interesting Facts
Corned beef is a type of salt-cured beef popular in North America, especially in the United States.
Swiss cheese is a type of cheese made in Switzerland that has a nutty, sweet taste.
Wonton wrappers are thin sheets of dough made from wheat flour and egg.