In a large bowl, whisk together egg and soy sauce until frothy.

Add turkey and green onions. Mix gently with your hands or fold with a rubber spatula until just combined.

Line a baking sheet with parchment paper. Fill a small bowl with water.

Lay a wrapper on a work surface. Place about 1 tablespoon turkey filling toward the bottom half of the wrapper (do not overfill dumplings or you'll have difficulty closing them).

Dip a fingertip in water and moisten edge of the wrapper.

Fold the top of the wrapper down, enclosing filling.

Use your fingertips to gently gather edges together, making small pleats to seal the dumpling.

Place on the prepared baking sheet. Repeat until you have used remaining filling and wrappers.

Place the baking sheet in the freezer until dumplings are frozen solid, about 2 hours. Transfer dumplings to resealable plastic bags and freeze for up to 3 months. (Always cook dumplings while still frozen.)

To serve, line a steamer basket with cabbage leaves.

Arrange 1 layer of frozen dumplings in the steamer basket over simmering water and steam until soft and cooked through, about 6 minutes.

Alternatively, cook pot sticker-style: Heat about 1 teaspoon oil in a skillet over medium-high heat.

Add frozen dumplings and lightly brown on each side, then add a small amount of water to cover the dumplings by about 1/3.

Cover and cook until dumplings are cooked through, about 6 minutes. Uncover and continue to cook just until the pan is dry and dumplings are hot.

Serve them with a flavorful dipping sauce like this easy one: whisk together 1/4 cup soy sauce, 1/4 cup warm water, 1 tablespoon rice vinegar, 2 teaspoons sugar, and grated fresh ginger and finely chopped garlic to taste.