When I was growing up in California, my grandmother, a fantastic cook, would prepare Saturday dinner and Sunday lunch for dozens of people every week. On public holidays, her entire family (six children, their spouses and 23 grandchildren) would gather for a feast. But when we got a phone call mid-week, it meant one thing: she’d found reasonably priced Dungeness crabs, and she’d be steaming them for dinner.
This was always a smaller group – about a dozen of us – and we’d eat our fill of crab before moving onto a few simple dishes, often congee with stir-fried vegetables.
This was my grandmother’s way of serving crabs, although in Hong Kong I use the easier-to-find, smaller types such as flower crabs or crucifix crabs. Mud crabs are good, too, but the shell is thick, making it difficult to crack the legs, and it’s hard to pull off the back shell. Don’t use hairy crabs, which are eaten primarily for their roe.
For smaller crabs count on at least two per person. One large mud crab should be sufficient for two greedy diners (I would include myself in that category) or four who are more restrained.
Take the crabs from the bag you brought them home in and lay them on a tray. Place the tray in the freezer and leave them for 10 minutes - this puts the crabs to sleep. (Don't leave them in the freezer for longer than 10 minutes, or they will be frozen.) Kill the crabs by pushing the sharp, slender blade of a boning knife, or a sharp skewer, through the face into the brain. Scrub the crabs with a clean kitchen brush under running water, then put them back-side down in the sink. Lift the “apron” at the base of the bottom shell (it’s long and slender on males, wide and bell-shaped on females) and pull it off. Turn the crab over. Holding down the claws with your left hand (if you’re right-handed), grasp the side of the top shell with your right hand and pull it up and away from the body to expose the insides. Set the top shells aside, placing them upside-down so the liquid and soft parts stay inside. From the body, remove the feathery gills, the intestines (they’re white and squiggly) and other inedible parts. Cut each body into four, making sure some of the legs are attached to each piece. (If you're using one or two larger crabs, cut the body into eight pieces: the two claws, then the body into six.)
Lay the body pieces in one layer on a large heat-proof platter, and the back shells on another platter. Pour some water into the base of a tiered steamer, or in a wok with a low rack with feet, and place the steamer or wok over a high flame. When the water boils, place the dish of crabs in the steamer or wok, cover with the lid and cook over a high flame for 10-12 minutes (you may need to steam them in batches). Larger crabs should be steamed for 15 to 20 minutes (or longer, depending on the size).
While the crabs are steaming, make the dipping sauce. Finely mince the garlic and put it in a small pan with the cooking oil. Set the pan over a low-medium flame and cook until the garlic is pale-medium golden; do not let the garlic get too dark, or it will taste bitter. Divide the soy sauce between four to six individual dipping bowls and pour the oil into each dish, making sure to distribute the garlic evenly. Serve the steamed crabs with the dipping sauce.