In a medium skillet, cook the bacon over medium heat, until browned and crisp, about 10 minutes. Drain on paper towels. When the bacon is cool, crumble into fine pieces and set aside for assembly.
Put the cold eggs in a large saucepan and add enough water to cover them by 1 inch. Add 1 tablespoon salt, then bring to a boil. Cover the saucepan and remove from the heat then let stand, covered, for 10 minutes.
Fill a large bowl with ice water. Remove the eggs from the saucepan, gently roll on the counter to crack all over, then place them in the cool water (the water will get under the membranes and make the eggs easier to peel). Once the eggs have cooled down, peel them, one by one. Pat the eggs dry then cut each egg in half crosswise.
Carefully remove the yolks and transfer to a large bowl. Mash with a fork, then sprinkle the vinegar over the yolks. Add the mayonnaise, mustard, cayenne, black pepper, and 1/4 teaspoon salt. Stir until well mixed and smooth. Taste and add more salt if needed to suite your taste.
Transfer the mashed yolks to a piping bag fitted with a plain or rosette tip. *Pro Tip: You can also use a resealable plastic bag: just snip a hole in a corner to create a quick piping bag. Pipe the yolks into the whites and garnish with the crumbled bacon and chives (if using).