1.Blend or process avocado, mayonnaise, chervil, chives, shallot, water and extra virgin olive oil until smooth, season to taste.
2.Heat 1 teaspoon olive oil to a large non-stick frying pan over high heat, cook prosciutto, in batches, 1 minute each side or until crisp, drain on paper towel. Quarter lettuce hearts lengthways, arrange on a platter. Coarsely crumble crisp prosciutto over, then drizzle with dressing. Scatter with ¼ cup extra fresh chervil leaves.