Fill a medium pan with cold water so it completely covers the eggs. Bring to a boil (without the eggs). Then salt the water a little and gently place the eggs at the bottom of the pan using a slotted spoon; set a timer to 12 minutes.

When done, remove the eggs from the pan and place them into a bowl with cold water.

Meanwhile, prepare the toppings. Place the onions into a small mixing bowl and pour in red wine vinegar. Let it marinate for at least 10 minutes, then drain well and set aside.

Fry the bacon over a medium-high heat until it’s reduced in size and turned a deep golden-brown color on both sides. Then, remove it onto a paper towel and let it dry until it becomes crispy. Lastly, finely chop the bacon and set it aside.

When cooled completely, slice the eggs in halves lengthwise. Remove the yolks and place them into a small mixing bowl.

Add the mayonnaise, mustard, vinegar, salt, and pepper, then mash everything using a fork until well combined and smooth.

Fill the egg whites with the egg yolk mixture using a teaspoon or a piping bag.

Top with crispy bacon bits and marinated onions and serve (for more topping variations, read the post above.)