Peel and slice the jicama into 1 by 3-inch strips about 1/8-inch thick; you should have 20 to 24 slices total. Cover with a damp towel and set aside.
Cut the avocados in half and remove the pits. Scoop the pulp into a bowl and mash with a fork. Add the tomato, bell pepper, jalapeno, salt, and lemon juice, and mix well. Taste and adjust the salt and lemon juice. Stir in the crabmeat.
Spread 1 tablespoon of the salad on each jicama slice, or serve as a dip with jicama as the crudite. This is not a make-ahead dish.
Recipe courtesy of Alexandra and Eliot Angle, Cocktail Parties with a Twist, Stewart, Tabori & Chang, 2002