Preheat the oven to 400 degrees F. Line a rimmed baking sheet with aluminum foil.

Cook the bacon until crisp in a large skillet. Remove the bacon using a slotted spoon, and drain on paper towels. Reserve 1/4 cup drippings in the skillet.

Combine the Brussels sprouts, olive oil and salt in a large bowl. Place the sprouts on the prepared baking sheet and bake until tender, about 20 minutes.

Add the vinegar, brown sugar and mustard to the reserved bacon drippings in the skillet. Cook over medium-high heat, stirring frequently, until the mixture is reduced by half, about 6 minutes. Pour the mixture over the sprouts, tossing gently to coat. Sprinkle with the bacon. Serve immediately.