Tuna Lettuce Cups

Name: Tuna Lettuce Cups
Prep time: 15 min
Total time: 15 min
Cuisine: American
Ingredients: 1 tin tuna in spring water; 1 celery stick finely chopped; 1 carrot finely chopped; 8 cherry tomatoes quartered and deseeded; 4" cucumber deseeded an chopped; 1/2 red chilli deseeded and finely chopped; 1 tbsp chopped coriander; 1 spring onion finely sliced; 1/2 small red onion finely chopped; Zero fat greek yoghurt to taste; Lemon juice to taste; Black pepper to taste; 1 little gem lettuce or similar