Heat the oven to 400 degrees F. Line 2 baking sheets with parchment paper.
Cook the bacon in a 12-inch nonstick skillet over medium heat until crisp. Remove the bacon from the skillet.
Add the onion and salt to the skillet and cook over medium heat for 5 minutes or until the onion is tender-crisp, stirring occasionally. Stir in the Brussels sprouts and cook for 3 minutes.
Stir the maple syrup, mustard and vinegar in the skillet and heat to a boil. Cook and stir for 5 minutes until the Brussels sprouts are tender and the maple syrup mixture is reduced. Stir in the bacon. Remove the skillet from the heat.
Sprinkle the flour on the work surface. Unfold the pastry sheet on the work surface. Roll the pastry sheet into a 12-inch square. Using a round cutter, cut the pastry sheet into 15 (3-inch) circles. Place the pastry circles onto the baking sheets.
Spoon about 2 tablespoons Brussels sprout mixture on each pastry circle to within 1/2-inch of the edge.
Bake for 10 minutes or until the pastries are golden brown. Let the pastries cool on the baking sheets on wire racks for 10 minutes.
Recipe Note: Parchment paper keeps the pastry from sticking to the baking sheet and also makes for easier cleanup. If you don't have parchment paper, you can spray the baking sheet with cooking spray instead. However, cooking spray may cause the bottoms of the pastries to brown more quickly, so begin checking for doneness 5 minutes early.
Per Serving: 107 calories;5.5 g fat;
11.8 g carbohydrates;
2.7 g protein;
3 mg cholesterol;
254 mg sodium.