Start by gathering your ingredients. Chop the red onion and hard-boiled eggs ahead of time. This step can save you minutes when you’re in a rush.

In a medium bowl, combine the drained tuna and chopped eggs. Use a fork to gently break up the tuna while merging it with the egg.

Stir in the finely diced red onion and the teaspoon of Dijon mustard. Mix everything gently, ensuring each bite contains a little bit of everything.

This is where the mayonnaise comes in. Add in one tablespoon to the bowl. Stir everything to combine. You’ll notice how this one addition transforms the mixture into something creamy and rich.

Sprinkle salt and freshly ground black pepper over the mix. Start with a little, then taste and adjust as needed. Remember, you want the flavors to shine without overpowering each other.

If you have time, let your salad chill in the refrigerator for about 30 minutes. This allows the flavors to meld together. If you can't wait, dig in right away!