Boil the Eggs: Place eggs in a pot and cover with cold water. Bring to a boil over medium-high heat. Turn off heat, cover, and let sit 10–12 minutes. Transfer eggs to ice water immediately.
Peel and Slice: Gently crack and peel the eggs. Slice lengthwise and scoop yolks into a bowl.
Mash Yolks: Mash yolks with a fork until fine crumbs.
Mix Filling: Add mayonnaise, Dijon mustard, vinegar/lemon juice, salt, and pepper. Mix until smooth.
Fill Egg Whites: Spoon or pipe yolk mixture into egg whites.