Soak vermicelli in hot water for 15 minutes; drain and set aside. In a wok, heat oil over medium-high heat until smoking. Stir-fry garlic and hot pepper flakes for 10 seconds. Add sugar, fish sauce and ketchup; stir-fry until sugar dissolves. Add vermicelli and eggs; stir-fry for 1 minute. Add ¾ cup (175 mL) of the bean sprouts and stir-fry for 2 minutes. Transfer to a serving platter, sprinkle with the remaining bean sprouts, green onions, peanuts and cilantro, and garnish with lime slices.