Step 1

Add the mayo, pickle relish, Dijon mustard, kosher salt, and black pepper to a small mixing bowl. Whisk to combine.

Step 2

Add the tuna, celery, sweet yellow onion, and red onions, and stir until completely incorporated. Cover and chill in the refrigerator until you are ready to serve. Serve with crackers, veggie sticks, or on a sandwich.