For the Dipping Sauce: Place the garlic, chilies, chili paste, and ginger in a mortar and pound into a paste. Transfer to a mixing bowl and add the remaining ingredients and mix until well blended. Transfer to a glass jar and cover with a tight lid. If refrigerated the sauce will keep up to 3 weeks.
Combine all salad ingredients and toss gently. Place about a cup of the salad mixture in individual pasta bowls. Top each with about two cups of the noodles. Set the prepared noodle bowls aside.
Combine the beef, lemon grass, fish sauce, soy sauce, and sugar in a mixing bowl and set aside.
Heat the oil in a large nonstick fry pan over high heat. Add the garlic ad onion and stir-fry for 30 seconds. Remove beef from marinade and stir-fry until just done, 3 to 4 minutes. Remove from heat.
Divide the beef topping among the prepared bowls and garnish each with peanuts and cilantro. Invite each guest to drizzle on 3 to 4 tablespoons of the dipping sauce. Have them toss the noodles several times with chopsticks to blend the ingredients.