HEAT a non-stick frying pan over medium-high. Add 1 tbsp oil, then chicken. Cook until golden-brown on both sides, 2 to 3 min per side. Remove to a plate and loosely cover to keep warm. Discard oil in pan, then partially fill with water. Bring to a boil over medium-high. Add asparagus and cook until tender-crisp, 2 min. Drain and immediately rinse with cold water. Pat dry. Divide romaine and watercress among 4 plates. Top with chicken, asparagus, radishes, grapes and cheese.
WHISK 2 tbsp oil with vinegar, tarragon, honey and Dijon. Season with fresh pepper. Drizzle over salads.