Preheat oven to 400 degrees F. Line a baking sheet with aluminum foil (avoid parchment paper), then coat with non-stick cooking spray, or heat a grill and coat a grill pan.
In a small skillet, heat the olive oil over medium heat. Add the garlic and cook until fragrant and beginning to brown, about 2 minutes, watching carefully so that it does not burn.
Add the balsamic vinegar, honey, mustard, salt, and pepper. Whisk and simmer until the mixture thickens; about 4 minutes.
Place salmon skin-side down on the prepared baking sheet or grill pan. Brush liberally with the glaze.
Bake for 5 minutes, then baste with the glaze, and continue to bake/grill 5 to 10 additional minutes, until the fish flakes easily with a fork and is cooked through.
Transfer the fish to a plate, skin side down. Allow the fish to rest for 10 minutes. Remove the skin and serve overtop the salad, at room temperature or chilled.