Scatter the lettuce and watercress over a serving platter.
Arrange the eggs, bacon, chicken, avocado, and tomatoes on top of the salad leaves.
Sprinkle the chopped chives over the salad.
To make the dressing, whisk together the vinegar and oil together.
Season to your tastes with the other ingredients and whisk
Serve the dressing on the side, or pour it over at the last moment before serving.