1. Trim lamb and place in marinade. Set aside.
2. Chop potatoes, place them in a pot covered with water and boil until tender.
3. Prep the remaining vegetables and gather all other ingredients.
4. Preheat the broiler.
1. In a large dutch oven, cook onions, carrots, and garlic. Remove from pan and keep warm.
2. In the same dutch oven, brown lamb, then set aside with the cooked vegetables.
3. Deglaze the pan with the wine, then make the red wine gravy.
4. Add cooked vegetables and lamb to the gravy, then season with tarragon, salt and pepper. Keep warm.
5. Drain potatoes, then mash with butter, milk, and cream until thick and creamy. Season as desired.