Using a sharp knife, pry mussels from shells. Discard shells. Wash mussel meat and drain well.
In a bowl, combine flour, cornstarch, salt, garlic powder and pepper. Dredge mussels in flour mixture to completely coat.
In a pot over medium heat, heat about 2-inch deep of oil. Add mussels, shaking off excess flour, and deep-fry for about 5 to 7 minutes or until mussels are cooked through and are golden and crisp. Remove from heat and drain in a colander set over a bowl. Serve hot with spicy vinegar dip.
For Spicy Vinegar Dip
In a bowl, combine vinegar, garlic, peppercorns, chili and salt to taste.
Do not overcrowd pot during frying, fry in batches as needed.