Four crabs doesn't yield a whole lot of crab meat - so if you want this to be more than an appetizer, better get a whole bunch of crabs!
I like to add a little flavor to the cooking liquid although it doesn't make a huge difference in the crab. One thing you can do is put your shells back in the liquid after the initial cooking and make a crab stock for later use. Make sure to skim off the scum that rises to the surface though. —The Perennial Plate
Bring a pot of water to boil with the ancho chiles, garlic, yellow onion, juice of one lemon, black pepper, oregano, and salt. Let it simmer for 5-10 minutes then bring it back to a boil and add the 4 crabs. Cook for 8-10 minutes, the crabs should turn a bright orange.
You can shock the crabs in an ice bath or leave them to cool. Crack the legs and body and remove the crab meat from each of the crabs. Make sure to use your fingers to sift through the crab, its easy to get shell mixed in.
Mince the sweet onion and dice the guajillo chili and set them in a small bowl. Use as much or little of the chili as you like, depending on your preference for spiciness. Add the juice of one lime and leave the mixture to marinate.
Remove the prickers from the cactus pads with a knife. Rub with olive oil and salt. Grill until nicely charred. Dice.
Dice the nasturtium flowers and leaves. Combine with cactus, lemon, cilantro, onion, salt and the crab. Don't add your lemon juice all at once, add to taste - you don't want to overwhelm the crab meat.
Serve on a warm corn tortilla with tomatillo salsa.
The Fastest and Easiest Tomatillo Salsa
Grill tomatillos, onion, and jalapeños until charred and cooked through. Put in the blender. Season with salt and a little lime juice.
Chef & activist Daniel Klein and cameragirl Mirra Fine are road-tripping around the United States, filming and editing The Perennial Plate -- an online weekly documentary series dedicated to socially responsible and adventurous eating -- as they go. See below for Perennial Plate's recipes, shared weekly with food52 from the road!