Combine the tuna with the celery, onion, pickles, mayo, olive oil, and mustard and stir until mixed well. Season with pepper to taste. Spread the tuna salad onto the tortilla and top with the cheese. Broil until hot and bubbly, taking care not to burn, about 2-3 minutes.
Recipe by Cooking With MicheleĀ® at https://cookingwithmichele.com/2014/12/building-better-tuna-melt/