Wash baby potatoes under cold water, then boil in a pot until fork-tender, approximately 15-20 minutes.

Preheat oven to 350°F (175°C) and bake sliced red onions for about 10 minutes until softened.

Blanch asparagus in boiling water for 2-3 minutes, then transfer to an ice bath.

Whisk together olive oil, vinegar, maple syrup, salt, and pepper in a mixing bowl.

Combine cooled potatoes, blanched asparagus, and baked onions in a large bowl; drizzle with vinaigrette and toss gently.

Cover and refrigerate for at least one hour before serving to allow flavors to meld.