Prep: Wash the salad greens if necessary, and set aside. Wash and dice the onion and celery and place in a medium mixing bowl. Drain the tuna and add to the bowl, flaking it with a fork into small pieces.
Mix: Add the mayonnaise, salt and pepper to the bowl and mix well to combine.
Enjoy: Place an equal serving of salad greens, tuna salad and sauerkraut in each bowl. Serve immediately and enjoy!
Notes
Sauerkraut: Make sure to look for raw sauerkraut with live cultures in the refrigerated section of the grocery store (shelf-stable sauerkraut made with vinegar doesn't contain any live probiotics.)
Meal prep: You can make the tuna salad up to 5 days in advance, store it in an airtight container in the fridge, and then easily assemble your salad in the morning.