Bring 6 quarts water to boil and add 2 tablespoons salt.
Drop chicory into water and cook until tender, about 4 to 5 minutes. Remove and refresh in cold water bath. Drain well on towels. In a 12 to 14-inch saute pan, heat olive oil until smoking. Fry chicory, still in bunches, until quite brown and crispy. Remove to paper towels and season with salt and lemon zest. Serve with calf's tongue immediately.