Finely mince raw shrimp until they are almost the consistency of a paste. Mix shrimp in a large bowl with ground pork, garlic, ginger, scallions, soy sauce, Shaoxing rice wine, sesame oil, sugar, salt, and pepper. Combine using a fork or mixing chopsticks until the filling is fairly smooth and paste-like.
Cook about a teaspoon of filling in a skillet on the stove until cooked through. Taste the cooked filling for seasonings and adjust salt and pepper in the raw mixture accordingly.
To Fill and Fold
Working 4 at a time, place a teaspoonful of filling onto the center of each wonton wrapper. (As you're working, keep the stack of wonton wrappers and the wontons you've folded covered with a damp towel so they don't dry out.)
Use your finger or a pastry brush to dampen the top and right edges of the wrapper with water. Fold the bottom left corner over the filling to meet the top right corner, forming a triangle. Press around the filling to remove any trapped air from the folded wonton.
Use your thumbs to gently cinch the wrapper around the filling at the bottom of the wrapper. This will pull the left and right "arms" of the triangle downward.
Dampen the right arm with water and pass it under the left arm, gently pressing in the middle to seal.
Make the Broth
In a large pot, combine chicken broth, scallions, ginger, garlic, rice wine, sesame oil, and soy sauce. Bring to a boil, reduce heat, and simmer for 15 minutes. Strain and discard solids. Season to taste with salt and white pepper.
Simmer the Wontons
Bring a large pot of water to a boil. Add the wontons to the pot in batches, gently stirring so they don't stick to the bottom, and being sure not to crowd them (they need to have enough room to float; I usually cook about 10 at a time).
Simmer for 2-3 minutes, until the wrappers are transparent and the wontons float in the water. The internal temperature of the filling should be 160 degrees F.
Place wontons in soup bowls with a few torn baby spinach leaves, if desired. Ladle hot broth over the wontons. Let stand for 2-3 minutes so the spinach leaves wilt. Garnish with sliced scallions and serve.
*Sliced ginger infuses the broth with a bit of heat. If you prefer a very mild broth, omit the ginger, or decrease the quantity.