For the octopus: Heat a deep heavy pot until ripping hot. Add the olive oil, and when it just begins to smoke (wispy tendrils, not seven-alarm, billowing smoke), carefully, but quickly add the octopus. Add the chiles, garlic, lemon and onion. Cover and reduce the heat to low. Gently simmer until tender, 45 minutes to 1 hour. Remove the octopus, and then strain out the liquid, discarding the solids.
Preheat a grill or wood-burning grill to high heat.
Quickly char the octopus, about 2 minutes per side. Remove from the grill and divide the head from the legs, and then slice the legs thinly.
For the salad: Mix together the octopus legs, lettuce, tatsoi, pork, cucumber, garlic and onions in a large bowl. Season with oil, vinegar and salt and black pepper. Garnish with flaxseed and fried leeks.
NotesThis recipe was provided by professional chefs and has been scaled down from a bulk recipe provided by a restaurant. The Food Network Kitchens chefs have not tested this recipe, in the proportions indicated, and therefore, we cannot make any representation as to the results.