Preheat oven to 350°F.
In a pan over medium heat, add olive oil and onions. Cook until soft and translucent. Add salt and pepper to taste.
Cut puff pastry into 12 squares. Score the inside making a rectangle and poke with a fork in the center. Bake for 10 minutes.
Remove from oven and increase oven temperature to 425°F. Spread the goat cheese in the middle of the tartlets and top with caramelized onions. Place back in the oven and bake for 10 minutes.
Remove stems off the strawberries and slice to create a fan.
Remove tartlets from oven and let cool. Once cooled, top with strawberries and drizzle with balsamic glaze.