1. Mix cucumbers, 1/4 cup (4 Tbsp.) dressing, 1 Tbsp. chives, 1 tsp. lemon zest and 2 tsp. lemon juice until blended. Refrigerate 30 min.
2. Combine all remaining ingredients; spoon into 8 mounds, 3 inches apart, onto foil-covered baking sheet, using about 2 Tbsp. salmon mixture for each. Flatten each to 1/2-inch-thick patty.
3. Heat broiler. Broil patties, 4 inches from heat, 3 to 5 min. or until salmon cakes are done and tops are golden brown. Serve topped with cucumber mixture.