In a large (12- inch) nonstick pan or stockpot, heat broth, onion, fish sauce, chili oil, ginger, chili flakes, coriander and cloves over high heat until simmering. Cook 5 minutes or until onion is soft.
Rinse frozen Alaska Crab legs/clusters under cold running water to remove any ice glaze; pat dry with paper towels. Discard towels. Cut crab clusters or legs into smaller sections with a large knife and shell (discard shell.)
Turn off heat and gently add crab to liquid. Return heat to a simmer.
Once simmering, cover pan and cook 4 to 5 minutes for frozen seafood or 2 minutes for fresh/thawed crab.
Place 1/2 cup noodles and a seafood portion in a soup bowl. Ladle on 1 cup broth. Garnish with mushrooms, sprouts, basil leaves, cilantro and lime wedge.