1Whisk together vinegar, olive oil, tarragon, salt and pepper.
Reserve 1 cup. Pour remaining dressing into a plastic ziploc bag; add chicken and marinate 30 minutes or more.
Grill or broil chicken for 15 to 20 minutes, turning once until fully cooked. Sliced thinly when cool enough to handle.
In a large bowl, toss together pasta, peppers, onions,Fontina Parmesan, reserved dressing and chicken.