2 cups honeydew melon, seeded and cut into 2-inch chunks
1 cup seedless cucumber, sliced into 1/4-inch thick rounds
3/4 cup crumbled Feta cheese
Pour vinegar into a small saucepan. Bring to a boil over medium-high heat. Reduce heat to medium-low and simmer until reduced to 1/4 cup (about 20 minutes). Stir occasionally. Remove from heat and cool.
Arrange melon and cucumber on a serving platter or individual plates. Sprinkle feta over salad. Drizzle, to taste, with balsamic reduction. Serve immediately.