In a large bowl, combine the mayonnaise, sour cream, capers and mustard. Add the shallots, celery, lemon zest and juice, and stir. Season with salt and pepper. Gently fold in the crabmeat, the chopped parsley and the tarragon.
Place the endive spears on a platter and spoon a heaping tablespoon of the crab mixture into the center of the leaves. Garnish with a sprinkle of chopped bacon.