Carefully pop out the yolks into a small mixing bowl, setting the egg white halves on a plate or deviled egg tray, cut side up.
Mash the yolks with a fork until they’re very fine and no large lumps remain. Add the mayonnaise and yellow mustard to the bowl.
Stir the yolk mixture until it’s smooth, creamy, and evenly combined. If it looks too thick to spoon easily, add a tiny bit more mayonnaise, a teaspoon at a time, until it’s soft and creamy but still holds its shape.
Using a small spoon (or a piping bag if you want to be a little fancy), fill each egg white half with the yolk mixture, mounding it slightly in the center.
Arrange the filled eggs on a white ceramic plate in a single layer. Sprinkle the tops lightly and evenly with paprika for that classic southern look and a pretty red contrast against the creamy golden filling.
Cover the plate loosely with plastic wrap and chill in the refrigerator for at least 30 minutes before serving so the flavors meld and the filling firms up just a bit. Serve cold and watch them disappear.
To keep this true to the 4-ingredient promise, I stick to just eggs, mayonnaise, yellow mustard, and paprika—but you can still play around within those basics. For a slightly tangier filling, increase the yellow mustard by 1/2–1 teaspoon, or use a spicy yellow mustard for a gentle kick without adding extra official ingredients. If you like a looser filling, add a touch more mayonnaise; for a firmer, more pipeable filling, use a little less. For meal prep, boil and peel the eggs a day ahead, then store them in an airtight container in the fridge; mix and fill the yolks the day you serve so the tops stay fresh and pretty. To transport to family gatherings, nestle the deviled eggs tightly on a plate, cover with plastic wrap, and set the plate inside a larger baking dish so it’s easier to carry without everything sliding around.