Lightly toast bread.
In small bowl combine avocado, lemon juice and horseradish. Divide into four portions and spread on bread. Top each sandwich with two slices of turkey and a pineapple slice. Spread 1 tsp mustard over each sandwich; sprinkle 1 Tbsp cheese over each and place under broiler, cooking until cheese is melted and lightly browned.
Servings: 4