Heat soy sauce in a small saucepan and dissolve the brown sugar. In a small mixing bowl, make a slurry with the vinegar and cornstarch and add the slurry to the pot to thicken the sauce. Remove from heat and let cool to room temperature.
Heat oil in deep fryer to 375 degrees F or follow the manufacturer's instructions for similar foods.
Lightly toast the bread and lay out on a work surface. Blend the garlic, ginger root, egg, cream, fish sauce and sesame oil in a food processor to make a paste. Add the rock shrimp and pulse to combine. Coat toast with shrimp mixture and sprinkle with sesame seeds. Deep-fry until golden brown and drain on paper towels. Serve with dipping sauce.