PREPARE THE SAUCE: Combine the vinegar and sugar in a small saucepan and bring the mixture to a boil over moderate heat. Boil just until the sugar is dissolved. Transfer the liquid to a small bowl. Add the garlic, pepper, and fish sauce. Set aside. MAKE

THE FILLING: Melt the butter in a skillet over moderate heat. Add the garlic and onion and cook until the onion is translucent, about 2 minutes. Add the celery, carrot and mushrooms, and saute until the vegetables are soft but not browned, about 2 minutes. Add the crabmeat, fish sauce and black pepper and toss well. Transfer the filling to a bowl and cool completely.

ASSEMBLE THE ROLLS: Stack the spring roll wrappers. Using a sharp knife or scissors, cut the stacked wrappers in half along the diagonal. Work with one triangle at a time, keeping the remaining wrappers covered with a damp kitchen towel to prevent drying. Place a triangle smooth side down on a work surface, with the long edge nearest you. Lightly brush the sheet with the flour paste. Place 2 heaping teaspoons of the filling along the lower edge of the wrapper, [then fold in points at the side over filling] and then roll up from the bottom to enclose the filling. Place the roll seam side down on a large plate and keep covered with a damp towel while you fill and roll the remaining triangles. Preheat the oven to 250F. Line a baking sheet with paper towels.

COOK THE ROLLS: Heat 2 inches of oil in a wok or deep heavy skillet to 350F. Gently add the rolls in batches and cook, turning occasionally, until golden brown, about 2 minutes. Remove with a slotted spoon to a sieve set over a large bowl to drain. Transfer the rolls to the baking sheet and keep warm in the oven while you cook the remaining rolls. Serve the rolls with the dipping sauce.

VARIATION: Crabmeat Triangles: Cut each spring roll wrapper into 3 strips. Place 2 teaspoons of the filling on a bottom corner of each strip and fold up and over flag-style to form triangles. Brush the end with flour paste before the last fold to seal. Fry and serve with the sauce as above. If you prefer to bake rather than fry these treats, wrap up the filling flag-style in strips of phyllo pastry to form triangles, spray or brush with butter, and bake in a preheated 375F oven until golden brown, about 15 to 20 minutes. Serve the triangles on their own, without sauce. *Cooks Notes: When buying fish sauce, look for the Squid or Tiparos brand. Once opened, fish sauce lasts up to a year at room temperature. Fish sauce is available in Asian markets and in some well-stocked supermarkets. Cooked salmon, lobster meat, or chicken may be substituted for the crabmeat. For additional flavor and texture, wrap the fried rolls in tender lettuce leaves, along with some sprigs of mint and coriander, before dipping into the sauce. Yield: 20 rolls for hors doeuvres, or enough for 4 to 6 appetizer servings. Source: Cooking Under Wraps

The fish sauce was missing from the ingredients so I found the original recipe at http://www.completerecipes.com/113281.htm and updated this one.