Combine ½ cup vegetable oil with 2 tbsp. minced lemongrass (1 stalk, trimmed and minced) in small saucepan over medium heat. Heat until lemongrass aroma is released and it sizzles, about 30 seconds to one minute. Add 2 tbsp. ground dried red chilies (hot) and cook for additional 15 seconds or until chilies also sizzle and get a shade darker. Remove from heat. Use this to top the noodles with oil before ladling in broth, and also serve some tableside for guest to add it as they want.