Cook the dumplings according to the package directions (panfrying is preferable to steaming). Meanwhile, in a large bowl, combine the vinegar, sugar, soy sauce, 1/4 cup water, and hot sauce (if using). Add the coleslaw mix and toss. Divide the slaw among individual bowls and sprinkle with the scallions and peanuts. Top with the cooked dumplings. Pour any sauce that remains in the bowl over the dumplings. Serve with additional soy sauce on the side.