Beijing Vegetarian Dumplings

Name: Beijing Vegetarian Dumplings
Prep time: 1 h
Total time: 1 h
Cuisine: Asian, Chinese
Ingredients: 2 cups napa cabbage or spinach, finely chopped; 2 cups chopped mushrooms (any kind); 1 teaspoon salt; 1 cup crumbled tofu; 1 bunch scallions chopped; 2 teaspoons finely chopped peeled ginger; 1 garlic clove, finely chopped; 3 tablespoons soy sauce, tamari or gluten-free soy sauce; 1 tablespoon sesame oil; 1 pkg store-bought round dumpling wrappers (sometimes called gyoza); 3 tablespoons soy sauce, tamari or gluten-free soy sauces; 2-3 tablespoons Chinese black vinegar (if hard to find, sherry or balsamic vinegar is okay); Optional chili oil, minced ginger or chopped scallions; 10-inch nonstick skillet or seasoned cast iron pan with a lid; Small rolling pin; Baking sheet lined with parchment; Plastic bag; Mixing bowls