Place the first 3 ingredients in a food processor, and process until minced. Add lime juice, fish sauce, and tofu; pulse until blended. Heat oil in a small skillet over medium heat; sauté ginger and garlic 2 minutes. Add to shrimp mixture, and pulse until combined. Add onions and chopped cilantro, and pulse 3 to 4 times. Spoon into a bowl; cover and chill 1 hour. Garnish dip with additional shrimp and cilantro sprig, if desired.
I made this a few years ago and have been looking for the recipe. I served it with wonton wrappers that I sprinkled w. five-spice powder, cut into strips and baked. I thought it was delicious.