Using 2 forks, shred the chicken and place it in a large bowl.
Add in the yogurt, mayo, mustard, shallot, garlic, lemon juice, and zest.
Season with sea salt and pepper to taste and stir to combine.
Create lettuce boats by doubling up two lettuce leaves so they are sturdier.
Fold in the avocado, then spoon it into your lettuce leaves.
Sprinkle with some chili flakes, if desired, and serve immediately.
Enjoy!