Before you start mixing, ensure you have everything within arm’s reach. It’ll make the process smoother and more enjoyable. Trust me, nothing interrupts the kitchen magic like searching for a misplaced ingredient.

In a mixing bowl, combine the creamy mayonnaise, Dijon mustard, and capers. Stir gently but thoroughly. This creamy base sets the foundation for the rich taste of your tartar sauce.

Next, add the tangy sweet pickle relish and finely chopped onion to the mix. This is where the sauce begins to take shape. Those ingredients introduce layers of flavor, so make sure they're evenly distributed.

Now it’s time to bring everything together with some salt, pepper, and optional lemon juice. I recommend starting with a small amount. You can always add more later. Taste as you go to ensure it’s just right.

Once all the ingredients are well combined, cover your bowl and let the sauce chill in the fridge for at least 30 minutes. This allows the flavors to meld beautifully, making every bite utterly delightful.