1. Combine 1 gallon water and the vinegar in a large stockpot over high heat. Cut the lemon in half crosswise and squeeze each half into the water mixture, adding each squeezed half to the water. Add the peppercorns, bay leaves, and salt and stir to combine. Bring to a boil, lower the heat, and simmer for 10 minutes.

2. Using tongs or wearing thick rubber gloves and holding the octopus by the head, dunk the octopus body into the simmering water 3 times, leaving it submerged for about 5 seconds each time. This is called “scaring” the octopus, because the tentacles will curl up as you plunge the octopus into the water.

3. Drop the octopus into the simmering water after the final dunking and bring to a boil. Simmer for about 30 minutes, or until tender. Remove from the heat, drain well, and set aside to cool. If not using immediately, cover and refrigerate for up to 8 hours.