Rinse the octopus and, if it hasn’t been cleaned, trim off the ink sac, beak, and eyes. Put it in a large pot and cover with cold water. Add the bay leaf, thyme, onion, garlic, chile, and coriander seeds. Add a splash of olive oil and a good pinch of salt. Cover the pot and bring just to a boil, then turn down the heat to low.
Simmer slowly for 45 minutes to an hour, never allowing the broth to boil. Check to see if the octopus is tender by probing with the tip of a paring knife. Remove the octopus from the broth and let cool to room temperature. (Reserve the savory broth to use in fish soup or Black Paella with Squid and Shrimp.)
When the octopus is cool, separate the tentacles with a sharp knife. Rub the tentacles with your fingers to remove any loose skin, then cut the tentacles into
To serve, pile the octopus chunks onto a platter. Sprinkle with salt and pepper and drizzle with olive oil. Dust lightly with pimentón. Surround with the pickled onions. Supply diners with toothpicks or small skewers for communal snacking.