How to Make It
In a small bowl, combine the shallot with the garlic, vinegar and lemon and lime juices. Let stand for 5 minutes.
In a medium bowl, beat the yolk with a whisk. Gradually add half of the olive oil in a thin drizzle, whisking constantly. Add 1 tablespoon of liquid from the shallot mixture, then whisk in the remaining olive oil. Add the avocado and mash it in with a fork. Whisk in the remaining shallot mixture and the herbs and season with salt and pepper.
Add the lettuce to bowls, top with some of the dressing and serve.