Prepare the wonton filling by finely chopping green onions and celery.

Combine the chopped vegetables with ground pork, soy sauce, cooking sherry, egg, and cornstarch in a large bowl.

Mix well to form the wonton filling.

Remove wonton skins from the package and keep them covered with a damp paper towel to prevent drying.

Take one wonton skin at a time and place a small spoonful of filling in the center.

Moisten two sides of the skin with water using your finger.

Fold the skin over to form a triangle and gently press the sides together to seal.

Moisten one of the end corners with water and gently press the two far ends of the wonton together.

Place the filled wontons on a cookie sheet and cover with a damp paper towel.

Freeze the wontons for about 2 hours, or until solid.

Transfer the frozen wontons to a freezer container or bag and store for up to 2 months.

Slice mushrooms and spinach into bite-sized pieces.

Julienne ginger into small pieces.

In a large stockpot, heat chicken broth, cooking sherry, and sugar over medium heat.

Add the ginger and bring to a simmer.

Add the mushrooms and simmer until they begin to soften.

Add the frozen wontons and cook for 8-10 minutes.

Add the chopped spinach and cook for 2-3 minutes more, or until wilted.

Serve the wonton soup immediately.