Spider Crab (Txangurro)

The single most consequential decision in cooking spider crab is made at the fishmonger's counter. Buy live whenever possible. A spider crab that has been dead even a few hours will have begun to degrade, developing an unpleasant ammonia note that no amount of seasoning can mask. The meat loses its sweetness and firms up in a way that is immediately detectable on the palate. Inspect the crab before purchase: the legs should be intact and responsive when touched, the underside membrane still moist and pliable, and there should be no detectable odor of ammonia or rot from the gills.

Request the crab dressed—cleaned of inedible viscera but with the coral (roe) and tomalley (liver) retained and packed separately—if you are making txangurro. Attempting to dress a spiny spider crab without experience is a reliable way to lose most of the leg meat to damage and scattering. A skilled fishmonger can have the crab dressed in minutes, and the separated coral and tomalley are essential to authentic results.

Killing a live crab humanely and cooking it properly are two distinct skills, both worth mastering. The recommended method is to chill the crab in a freezer for 20 minutes first—this slows the metabolism and dulls its response, making the process less distressing and easier to execute cleanly. Then insert a sharp knife through the underside membrane directly into the nerve cluster behind the eyes (the apparent 'brain'), and immediately plunge the crab into a pot of actively boiling, heavily salted water. This sequence—chill, pierce, boil—ensures rapid, certain death and prevents the crab from shedding limbs in the pot.

Cooking time is 10–12 minutes per kilogram of live weight in actively boiling salted water. Do not cover during boiling—the steam creates turbulence that damages the delicate leg meat. After the timer expires, remove the pot from heat, cover it, and allow the crab to rest in the hot water for a further 5 minutes. This carryover cooking completes the process without the risk of boiling agitation. Overcooked spider crab meat turns rubbery and acquires a grainy, chalky quality that betrays all the sweetness. Dress the crab while still warm: the meat releases from the shell significantly more easily at temperature.

Txangurro a la donostiarra is not simply 'crab gratinéed in its shell'—it is a precisely constructed filling that treats the crab's own flavors as an orchestra. The coral and tomalley are the foundation; they provide an oceanic depth and natural richness that no amount of stock or butter can replicate. Build the filling by softening finely minced onion in good olive oil, adding a small amount of concassé or cooked-down tomato for body and acidity, then deglazing with a generous splash of sherry—Amontillado or Oloroso—and allowing it to reduce by half. Fold in the reserved crab meat, then the coral and tomalley, and finally bind with a mayonnaise made from the hard-boiled egg yolks and a fragrant olive oil. The mixture should be assertive: sherry, garlic, olive oil, and a touch of acidity must stand up to the crab's delicacy, not retreat from it.

Refill the cleaned shell generously—rounded and slightly overflowing is correct—top with a thin ribbon of mayonnaise, and run under a very hot broiler for 5–8 minutes until the surface is bronzed and bubbling at the edges. Serve immediately in its shell, with crusty bread to accompany the filling.