In a large bowl, combine shrimp, garlic, scallions, soy sauce, fish sauce, cilantro. Blend well, and let stand for 15 minutes.
Place about one teaspoon of the filling at the center of each wonton skin. Moisten all 4 edges of wonton wrapper with egg yolk, then pull the top corner down to the bottom, folding the wrapper over the filling to make a triangle. Press edges firmly to make a seal. Bring left and right corners together above the filling. Overlap the tips of these corners, moisten with egg yolk and press together. Continue until all wrappers are used.
Bring the chicken broth, fish sauce and sweet rice wine vinegar to a rolling boil. Gently drop the wontons into the broth. The wontons are cooked once they float to the top and you boil the dumplings for an additional 3 minutes. Garnish with chopped scallions, and serve.