Open-Faced Chicken Reuben Sandwich

Ingredients

• 1/2 cup plain yogurt
• 2 tsp balsamic vinegar
• 1 hard-boiled egg (finely chopped)
• 2 tsp pitted green olives (minced)
• 2 tsp red bell pepper (minced)
• 1/2 tsp Worcestershire sauce
• 4 slices whole wheat bread
• 3 cups cooked chicken (shredded)
• 2 cups cabbage (shredded)
• 1 tomato (sliced)
• 4 slices light-style Swiss cheese
• 2 tsp non-hydrogenated soft margarine or canola oil