How to Make It
Combine vinegar and sugar in a saucepan; bring to a boil. Simmer 5 minutes or until sugar dissolves. Add cucumber and onion. Cool to room temperature, stirring, 25 minutes.
Remove the vegetables with a slotted spoon; place in a bowl. Add fennel and olive oil, tossing to combine. Season with salt and pepper.
Preheat broiler. Line a shallow baking pan with foil; coat lightly with olive oil cooking spray. Arrange the salmon in a single layer on the pan. Combine the maple syrup and remaining ingredients; spread onto salmon. Broil salmon for 6 minutes or until just cooked through. Portion into 4 servings. Divide the salad among 4 plates; top with salmon.