For the Broth, heat oil in 6-quart stockpot over medium-high heat. Add onion; cook and stir until tender, about 3 minutes. Stir in stock, curry paste, soy sauce, brown sugar, garlic powder and ginger. Bring to boil. Reduce heat to low; cover and simmer 20 minutes. Stir lime juice into broth just before serving.
Meanwhile, for the Tangy Chili Sauce, mix all ingredients in small bowl. Cover and refrigerate until ready to serve.
Place sliced steak on a plate. Place garnishes in bowls.
To serve, pour broth into 6-quart electric hot pot or preheated slow cooker. Allow guests to cook steak in broth about 2 to 3 minutes or until desired doneness.
Let each guest customize their own bowl. Place some cooked lo mein noodles in bowl then ladle broth and steak over noodles. Stir in some Tangy Chili Sauce and top with remaining garnishes as desired.
Multifunction Electric Pressure Cooker Method (Saves 1 hr. cooking time): Heat oil on medium sauté setting in pot of multi-function electric pressure cooker (instant pot). Add onion; cook and stir until tender, about 3 minutes. Stir in stock, curry paste, soy sauce, brown sugar, garlic powder and ginger. Cover and lock lid into place. Set to cook 10 minutes on high pressure (or Soup setting). Vent pot and release pressure before opening and carefully remove lid. (Check manufacturer’s manual for safe operating instructions.) Set on low sauté setting. Stir in lime juice. Allow guests to cook steak in broth, about 2 to 3 minutes or until desired doneness. Customize individual bowls and serve as directed.