Step 1Shell the fava beans from the pod and blanch them in boiling water for about 1 1/2 minutes. Drain the beans and shock them in cold water, then peel the outer skin. One pound fresh whole beans will yield a little more than one-third cup cooked, shelled beans.
Step 2Place the crab in a bowl and add the lime and orange juices, oil, salt and hot sauce. Toss gently to mix.
Step 3Add the beans, avocado and 2 tablespoons of the chives and gently toss again. (If you want to make this in advance, wait to add the avocado until just before serving; chill the mixture.) Taste and adjust the seasoning.
Step 4Lay the 2 best-looking lettuce leaves on 2 small serving plates. Cut the remaining leaves in half lengthwise, then crosswise into half-inch side strips. Toss with the crab mixture, then divide between the lettuce leaves on the plates, mounding attractively. Sprinkle the remaining chives over and serve.