Prepare spinach and mushrooms
Place in a large serving bowl and set aside
In a 10" sauté pan, sauté bacon until almost crisp
Add onion and brown sugar and cook until onions begin to caramelize (approximately 2 minutes)
Add wine, Texas tarragon, and dressing. Bring to a boil
Pour dressing over spinach and mushrooms. Allow to stand a minute for spinach to wilt
Toss and serve