In bowl, whisk eggs until blended. In second bowl, mix panko and sesame seed. Dip 1 chicken breast in flour to coat; pat off excess. Dip into eggs, then into panko and sesame seed mixture, coating both sides evenly. Place on parchment-lined sheet pan. Repeat with remaining chicken. Refrigerate.
For each serving, to order: Heat butter or oil in non-stick pan. Sauté 1 chicken breast 8 to 10 minutes or until golden brown, turning once. Drain on paper towels. Mound 1 cup watercress on plate. Slice chicken on the diagonal; arrange on watercress. Garnish with 4 tomato wedges and 2 cilantro sprigs; drizzle with salad dressing.