Remove and discard the dark green outer leaves from the cabbages. Cook the remaining leaves for 5 minutes in boiling salted water. Place blanched leaves in ice water to stop the cooking. Drain. Cut away the stems. Thinly slice the cabbage leaves. Plunge the lobsters into boiling water, cover immediately and cook for 4 minutes. Drain. Remove and shell the tails and claws from the lobsters. Split and open the heads, reserving the coral. Melt 2 tablespoons of butter in a frying pan and add the crushed lobster heads and claws, the shallots and tarragon. Add enough water to just cover the shells. Bring to a boil and boil hard until reduced to 1 cup. Strain into a small saucepan. Whisk the coral into the cooking liquid and bring to a boil. Cut the lobster tails into medallions. Melt the remaining butter in a large saucepan and sautÄ the cabbage and lobster medallions. In a separate frying pan heat some olive oil and sautÄ the lobster claws. Season with salt and pepper. Drain on paper towels. To serve, place the lobster pieces on a platter with the cabbage and spoon the sauce.