If using raw crabs, srub them with a scouring brush under cold running water, then plunge them into a deep pot of lightly salted boiling water-about 6 cups (48 fl oz/1.5 L). Cook for 10-15 minutes, depending liquid. Clean crabs by pulling off a
pron flap from under shell. Pry off top shell and rinse away breathing ducts or lungs. Break or cut body in half, or cut large crabs into smaller pieces. Twist off claws, reserving pincers for garnish. Refrigerate until ready to use.
Soak mushrooms in hot water for about 20 minutes, then drain, squeezing to remove all liquid. Use shears or a small knife to cut away tough stems, and discard. Cut mushroom caps into thin julienne, then crosswise into small dice; set aside.
In a large pot, bring 6 (48 fl oz/1.5 L) reserved liquid from cooking crab, or stock if using precooked crab, to a boil. Peel asparagus, cut off about 1 1/2 inches (4cm) of tips and set aside. Chop remaining asparagus into thin rounds. Add asparagus tips to boiling liquid and cook for 2 minutes. Using a slotted spoon, transfer asparagus tips to a bowl. Whisk in egg white. At the last minute, add crabmeat and mushrooms. Stir to combine and remove from heat. To serve. Garnish with cilantro sprigs and reserved asparagus tips.

Serves 6

Note: This is a specialty of the mile-high city of Dalat, where it is made with thich-shelled mud crab transported by truck daily from the coast. The soup is especially popular in summer, when the crabs taste sweetest and render their juices best.

Ingredients

2 lb (1 kg) raw or cooked crab in its shell, or 1 lb (500g) lump crabmeat, picked over for shell
25 dried black mushrooms
6 cups (48 fl/ oz/1.5 L) water, or if using precooked crab Quick Seafood Stock or Fish stock
6 Spears asparagus, trimmed
1 tablespoon arrowroot or cornstarch (corn flour) dissolved in 1 tablespoon water.
1 teaspoon Salt
1/2 teaspoon ground pepper
1 egg white
1/3 cup (1/2 oz/15g) coarsely torn fresh cilantro (fresh coriander) sprigs.