Preliminaries: Soak noodles in warm water to cover for 30 minutes. Procedure: Trim any fat or sinew off the chicken and cut the breasts across the grain into 3-inch-by-1/4-inch strips. Shell and devein the shrimp. Seed and mince the chilies. Mince the garlic and ginger. Finely chop the onions, reserving the green part for garnish. Combine the fish sauce, vinegar and sugar in a small bowl. Cook the noodles in rapidly boiling water for 1 minute or until tender. Refresh under cold water, drain and blot dry on paper towels. Toss the noodles with 2 teaspoons vegetable oil. Heat a large wok or skillet over medium-high heat and add the rest of the vegetable oil. Fry the chilies for 30 seconds. Add the garlic, ginger and onions and stir-fry until tender. Do not let brown. Add the chicken and stir-fry until cooked. Stir in the shrimp and fish sauce mixture and cook until the shrimp turns pink. Make a well in the center of these ingredients and add the egg. When the egg starts to set, stir to scramble it and toss with the other ingredients. Stir in the noodles, bean sprouts and half the peanuts. Cook the pad thai just until the bean sprouts begin to wilt. (If the pan is too small, work in two batches.) Transfer the mixture to a platter and sprinkle with the remaining peanuts and onions. Garnish with lime wedges and mint leaves and serve. Yield: Makes 4 servings. Nutritional info (per serving): 463 calories, 23 grams fat, 192 milligrams cholesterol, 667 milligrams sodium.