Method

1. Begin by making the tuna mayo. 
2. Mix together the tuna, mayonnaise and capers in a bowl. 
3. Add lemon zest to taste. 
4. Finely chop the leek and add in. 
5. Season to taste with salt and pepper. 
6. Add lettuce to the bread. 
7. Add the tuna mayo and serve. 

Tip: Make a larger batch of tuna mayo and keep covered & refrigerated, so your next sandwich will be ready in a flash!