Butcher the live crab: Pry open its carapace by inserting a chef’s knife through the slit at the bottom of its body. Set the top shell aside. Use scissors to snip off the feathery gills, and the rubber bands around its claws, and discard them. Remove and discard the abdominal flap, also known as the tail flap, found curling up the underside of its body. Once this piece is removed, you can use your knife to easily section the body lengthwise down the middle. Next, section it again crosswise, so that you have four pieces of meaty crab, each with two legs attached. Finally, twist off the claws and cut off the leg pointy tips with scissors (this will allow the seasoning to penetrate the legs).
Spread the potato starch or cornstarch onto a plate, then dust each piece of crab with the starch, focusing on the soft, exposed parts. I like to do this to the top shell as well, because someone will want to suck all the jus out of it.
Heat the oil to 375℉ in a wok or a deep pot. Fry the crab, one or two pieces at a time, for one minute on each side, then remove and set it on a rack to drain. Skim off any debris from the oil. Refrigerate the crab until ready for pickup.
Let the oil temperature drop to 250℉, then put the minced garlic into a fine mesh strainer and set the strainer in the oil. Since the garlic has so much liquid, the oil temperature will drop and will stay low until nearly all the water is gone. Slowly fry the garlic, stirring gently with a spatula, for about five minutes, until the garlic is foamy and light golden. You’ll know it’s almost done when the temperature of the oil begins climbing again. Remove the garlic from the wok and pour it onto a paper towel to drain; it will keep cooking if you leave it in the strainer.
Let the oil come back up to 350℉, then fry the panko breadcrumbs, using the same strainer-in-pot method you used with the garlic, until the breadcrumbs are golden, about two minutes. Remove them from the wok, drain them on paper towels, and mix them with the garlic in a medium bowl.
Season your garlicky breadcrumb mixture with the salt, sugar, cayenne pepper and ground Sichuan pepper, using a spoon to toss everything together. Set the mixture aside until ready for pickup.