Place chicken broth in a large skillet, place chicken breasts in skillet and cook in one layer until tender, turning them halfway cooking. Remove the skillet from the heat, once the chicken is tender and allow to cool in the broth 30 minutes.
Cook bacon over medium heat in a skillet until crisp. Remove bacon from the skillet and transfer bacon to paper towel to drain fat. Reserve 2 tablespoons of the fat for later.
Place in a blender, cooked egg yolk, lemon juice, mustard, reserved fat from bacon, oil, salt and pepper to taste. Add bacon and blend 5 to 7 seconds.
Remove chicken from the broth and place it on a chopping board. Dry and cut it into cubes.
Place avocado cubes in a bowl and mix with lemon juice, chicken cubes, celery and onion. Pour vinaigrette on top and mix well.
Place lettuce leaves on each plate and serve salad on top. Garnish with tomato slices.