Part 2/6:
- ½ cup of finely diced celery. 
- ½ cup of finely diced onion. 
- Mayo: 1 to 1¼ cups of mayonnaise (Hellmann’s is recommended for its thick texture). 
- Optional Thickness: Crush some crackers or use bread to absorb excess moisture if needed. 
- Bread for Serving: Rye bread and New York deli rolls (hard rolls) are traditional, but feel free to use what you like. 
- Cheese: American, cheddar, or Swiss cheese for a tuna melt, if desired.