For tarragon sauce, in small bowl combine mayonnaise or salad dressing, green onion, the 1 teaspoon snipped parsley, tarragon, and pepper. Stir to mix. Cover and chill until serving time.

In medium mixing bowl combine egg, celery, green sweet pepper, bread crumbs, onion, the 1 tablespoon snipped parsley, Worcestershire sauce, and salt. Add chicken; mix lightly but well. Shape into four 4-inch oval patties.

In large skillet cook chicken patties in hot oil over medium heat for 10 to 12 minutes or until an instant-read thermometer inserted in side of patty registers 165 degrees F, turning once. Spread each cut side of croissants with some of the tarragon sauce. Arrange a lettuce leaf and a chicken patty on bottom half of each croissant. Top each with additional tarragon sauce and croissant top. Serve with tomato slices. Makes 4 sandwiches.

Prepare tarragon sauce up to 24 hours ahead; cover and chill.