In a small bowl, combine the mayonnaise, scallion and brandy, mixing well.
For each sandwich, spread three pieces of bread with a portion of the mayonnaise mixture.
Cover the first slice of bread with lettuce leaves, 2 ounces of crabmeat, and one or two tomato slices.
Add the second slice of bread, and top with the four half-slices of bacon, a layer of avocado slices, another tomato slice or two, and more lettuce.
Cover with the third slice of bread, secure the sandwich with wooden picks, if you like, and slice it in half.
Serve the sandwiches immediately.
