1) In a small bowl, whisk together all of the dressing ingredients and set aside.
2) Slice the ham into 1cm strips. Spray a nonstick frying-pan with cooking spray and preheat over a medium-high heat. Add the ham to the frying-pan and cook over stirring frequently, until the ham is warmed through and crisped, 3 to 5 mins. Remove from the heat and set aside.
3) Remove and discard the yolk from one of the hard boiled eggs. Chop the remaining egg white and whole egg and set aside.
4) In a large bowl toss the romaine and watercress with two thirds of the dressing. Put the dressed greens onto a large serving dish. Place the tomatoes on top forming a row down the middle. In strips on either side of the tomatoes place the avocado, chicken, cheese, diced egg, and the crisped ham on top of the greens. Drizzle with the remaining dressing and serve.