I recently pickled some octopus and there was a call for the recipe, so I thought I'd post my source, from the incomparable Diana Kennedy's militantly authentic The Art of Mexican Cooking (p. 199). The flavor is wonderful, and the presentation is absolutely show-stopping -- tiny purple-pink baby octopi, their little tentacles curled up by the cooking, mottled with black ink spots and set off by green peppers and surrounded by the scents of vinegar and onions and Mexican oregano. I served them as appetizers, straight from the pickle (as Kennedy suggests), but they would look wonderful slightly warmed and served over white rice.
4 tablespoons fruity olive oil
2 pounds cleaned octopus*
4 garlic cloves, peeled and roughly chopped
sea salt to taste
1 large white onion, cut into thin rings
1 small green bell paper, seeds and veins removed, diced
1 teaspoon crumbled oregano, Yucatecan if possible [I subbed Pueblan oregano.]
3 California bay leaves, roughly broken up [or add a fourth European bay leaf]
1/4 teaspoon coarsely ground black pepper
4 chiles güeros or Fresno or wax chiles, charred [over a gas burner or under a broiler, turning regularly] and kept whole, unpeeled [I used Hungarian.]
1 cup mild vinegar [Pineapple's most traditional. I used white, though I think cider would have improved it.
Heat the olive oil in a heavy pan, add the octopus pieces and garlic, sprinkle with salt, and toss, almost stir frying, for about 5 minutes. [I might have overdone this step slightly, as I was using very small octopi, which I kept whole, on which see note below. A mere minute or two might have been better.] The octopus should be tender but al dente. Transfer half the octopus and juice to a small, deep enamel or stainless-steel pan. Cover with half the onion rings, the green pepper, half the oregano, and the bay leaves. Cover with the rest of the octopus and the remaining ingredients, and continue simmering, covered for about 10 minutes. Taste for salt and set aside for at least 2 hours or overnight.
*A note on cleaning octopus: I'm really not clear on the best way to do this (though I imagine there are YouTube videos to e, but the three main points seem to be: 1) remove the ink sac and organs from the tubular "head" space (this was already done on the octopi I purchased from Pete's Fresh Market on Cermak, just west of Western, 2) dig out the hard beak from it's mouth hole on its bottom, and 3) dig out / slice off the eyes. I tried to keep the little critters as whole as possible for presentation's sake. Kennedy stresses the importance of obtaining octopi that weigh less than a pound a piece -- mine weighed in at only a few ounces a pop.