1. Brown pork with ginger in a nonstick skillet over medium-high heat, stirring often, 5 minutes or until meat crumbles and is no longer pink.
2. Combine pork mixture, cilantro, and 2 Tbsp. hoisin sauce in a medium bowl.
3. Arrange 1 won ton wrapper on a clean, flat surface. (Cover remaining wrappers with a damp towel to prevent drying out.) Moisten edges of wrapper with water. Spoon about 1 Tbsp. pork mixture in center of wrapper; fold 2 opposite corners together over pork mixture, forming a triangle. Press edges together to seal. Cover with a damp cloth. Repeat procedure with remaining wrappers and pork mixture.
4. Bring broth and remaining 1 Tbsp. hoisin sauce to a light boil in a Dutch oven over medium heat; gently stir in 8 dumplings. Cook 4 to 5 minutes or until dumplings float to top. Place dumplings in 5 individual serving bowls. Repeat procedure with remaining 7 dumplings.
5. Add mushrooms and onions to simmering broth; cook 1 minute. Ladle 1 cup broth mixture over dumplings in bowls. Garnish, if desired. Serve immediately.
Note: To freeze dumplings, assemble as directed, and place in a single layer in a large zip-top plastic freezer bag. Freeze up to 3 months. Cook as directed.