In a large skillet, combine fish stock, soy, lime juice, sherry, black beans, cashews, green onions, and cilantro. Simmer for 5 minutes or until sauce is starting to thicken. Add the cleaned crabmeat and cornstarch mixture and cook for 1 minute.
Meanwhile, in a large wok over high heat, add the peanut oil. When oil is hot, add the garlic, ginger, chile, and crab pieces and stir-fry for 3 to 4 minutes.
Serve crab pieces with sauce over top and steamed bok choy on the side. Be careful to not to eat any pieces of shell!