Created by Dee Ben on September 22, 2025
Step 1: Onions: In a heatproof container add the onions.
Step 2: In a small saucepan, combine vinegar, salt, and sugar and bring to a boil over high heat.
Step 3: Pour over the onions and use a fork to press onions down so they are submerged beneath the brine. Let sit until cooled to room temperature.
Step 4: If desired, you may make these pickled onions up to 1 week in advance.
Step 5: Store them tightly covered and refrigerated.
Step 6: Sandwich: In a medium bowl, stir together tuna, mayonnaise, celery, relish, dill, mustard, pepper, garlic, and 1 teaspoon of the pickle brine from the red onions.
Step 7: Taste and add salt if needed.
Step 8: Lay 1 piece rye bread on a cutting board and top with lettuce.
Step 9: Pile the tuna salad on top.
Step 10: Top generously with pickled onions, then avocado slices, and set the second piece of bread on top. Serve with pickle spears on the side.