Begin by bringing a pot of salted water to a boil over high heat. Once boiling, add the Brussels sprouts and cook for 4-5 minutes until bright green and tender but still firm. Drain and transfer to ice water to stop cooking.

In a large skillet, heat over medium heat and add diced bacon. Cook for 7-8 minutes, stirring occasionally, until crispy and golden brown. Transfer bacon to paper towels to drain excess grease.

Increase heat to medium-high and add the blanched Brussels sprouts and pecans to the skillet. Cook for about 4-5 minutes, stirring occasionally until browned and crisp on the outside.

Sprinkle ground mustard over the vegetables, then pour in the bourbon or apple cider vinegar to deglaze the skillet. Scrape up any browned bits and cook for another 2-3 minutes until the liquid reduces slightly.

Return the crispy bacon to the skillet along with the maple syrup. Toss everything together and cook for an additional minute until heated through and the sauce thickens slightly. Season with salt and pepper to taste before serving.