Prep your lettuce: wash and pat dry. Carefully pull the leaves off and set them on a plate. Think of them as tiny edible bowls.
Mash the avocado in a bowl until smooth. It should look creamy but still have some texture—no guacamole chaos here.
Add tuna, mayo (or yogurt), lemon juice, celery, and onion to the avocado. Stir until well combined. Season with salt and pepper to taste. If you’re feeling fancy, toss in cilantro or paprika.
Taste and adjust. If it’s too thick, a splash more lemon juice or a teaspoon of water helps. If too bland, a pinch more salt—no mystery here.
Spoon the tuna-avocado mixture onto each lettuce leaf. Fold or roll the leaf like a tiny burrito, and you’re ready to crunch into happiness.