Dissolve gelatin, garlic salt, salt, and pepper in boiling water.
Add sour cream, mayonnaise, vinegar, and anchovies.
Beat until well blended.
Pour into two 8 inch square pans.
Chill until firm, at least 1 hour.
Just before serving, cut gelatin into small cubes, about 1/2 inch square.
Pile gelatin cubes in center of shallow bowl.
Arrange salad greens, crabmeat and avocado around edge