Separate lettuce into leaves. Wash and spin dry.
Wash and dry remaining fresh produce.
Drain tuna and transfer into a large salad bowl. Flake with a fork.
Seed and small dice peppers and add to salad bowl.
Halve the avocados and slice up the flesh before scooping into the salad bowl.
Using a knife, shave the cilantro leaves from the stems. Discard stems and finely chop the leaves.
Small dice onion and add to the salad bowl.
Juice the lime and add to salad bowl.
Mix together dressing:
6 tbsp mayonnaise
1 tbsp dijon mustard
1 tsp salt
1/2 tsp black pepper
1/8 tsp cayenne pepper
Spoon the salad into doubled up leaves and enjoy.