First, tenderize the octopus by simmering it at a low boil for about an hour. Then char it on the grill to crisp the skin.
1small octopus, cleaned (about 5 pounds)
1cupdry white wine
2heads of elephant garlic, cloves unpeeled, separated
1sprig fresh rosemary
6plum tomatoes, cored
5tablespoons(or more) extra-virgin olive oil, divided, plus 3/4 cup
Kosher salt and freshly ground black pepper
1/4cupred wine vinegar
3poundskale, center stalks removed, leaves torn into 4" pieces
1 1/2cupsdried cannellini or pinto beans, cooked according to package directions
Place octopus and wine in a large pot. Peel 2 garlic cloves; add to pot. Add enough water to cover by 2". Bring to a boil, reduce heat to medium, and simmer until octopus is tender, about 1 hour. Transfer to a plate; let cool. Cut octopus into 4" pieces. Remove as much of slippery outer purple coating as possible without removing suction cups.
Meanwhile, preheat oven to 500°. Add whole tomatoes, drizzle with 3 tablespoons oil, and season lightly with salt and pepper. Toss to coat. Roast 30 minutes, stirring occasionally, until tomatoes are blistered and slightly charred. Let cool.
Whisk 3/4 cup oil, and vinegar in a small bowl. Season vinaigrette to taste with salt and pepper. Set aside.
Heat remaining 2 tablespoons oil in another large pot. Working in batches, add kale and cook until softened and slightly browned, adding additional oil by tablespoonfuls if dry. Season to taste with salt. Transfer kale to a large bowl and toss with 1/4 cup of coriander vinaigrette.
Prepare a medium-hot fire in a charcoal grill, or heat a gas grill to medium-high. Warm 3 cups cooked beans in a small pot with 1/4 cup of vinaigrette. Toss octopus with half of remaining vinaigrette; grill until charred, about 3 minutes per side.
Divide tomatoes, garlic, kale, and beans among plates. Top with grilled octopus, drizzle with some vinaigrette, and season to taste with salt and pepper.