Preheat the grill to high heat. Lay the baguette slices out on a large baking sheet and drizzle with 2 tablespoons olive oil. Sprinkle with salt and grill for 1-2 minutes per side, until toasted. Remove from the grill and set aside.
Then drizzle 1 tablespoon oil over the baby octopus. Salt and pepper liberally. Place them across the grill. The tentacles will begin to curl up. Flip and turn the octopus on both sides and the bottom, grilling about 8-10 minutes total. The texture should be just slightly rubbery, but still soft.
While the octopus is cooling, place the chopped tomatoes, garlic and basil in a large bowl. Then cut the tentacles off the octopus and chop the tentacles and entire body into small bite-size pieces, removing only the bit of gristle in the main cavity. Add the octopus to the bowl and drizzle with lemon juice and 1 tablespoon olive oil. Toss and salt and pepper to taste.
To serve: Scoop the grilled octopus bruschetta onto the pieces of crostini. You can drizzle them with balsamic glaze for extra sweetness, but I like them as-is.