Pour the tuna in a small mixing bowl. Use a fork to break the tuna chunks into very small pieces.
Add the basil, celery and lemon juice to the bowl. Use the fork to stir all the ingredients together till well mixed.
Add extra virgin olive oil to moisten the tuna to your liking. I usually use between 1 and 2 tbsp. Season with salt and pepper to taste; sea salt and freshly ground pepper is best. Serve.