Make sure you’ve got all your ingredients at hand. It’s always helpful to prep them in advance.
Open the cans of tuna and drain them thoroughly. This is crucial because excess moisture will lead to a soupy salad.
In a medium bowl, combine the light mayonnaise, low-sodium soy sauce, Dijon mustard, and lemon juice. Whisk these ingredients together until smooth.
In a larger bowl, mix the drained tuna, diced celery, and minced red onion. Gently fold in the dressing. You want everything to be well-coated without breaking up the tuna too much.
Cover the bowl with plastic wrap and refrigerate for at least 30 minutes. This allows the flavors to meld beautifully.
Once the tuna salad has chilled, stir it again briefly and serve it cold. Enjoy it on a sandwich, with crackers, or even on a bed of greens.