Clean the turkey, rinse, and pat dry. Stuff the turkey with all the ingredients then transfer to roasting bag.
For the marinade place all the ingredients in blender and blend together for a smooth consistency. Pour marinade into roasting bag. Smear all over turkey. Tie bag and arrange turkey, breast side down, in a large heavy roasting pan. Refrigerate overnight.
Let turkey stand in a bag at room temperature for 1 hour. Turn breast side up. Create steam holes in bag if required by manufacturer's instructions.
Preheat oven to 400°. Roast turkey for 30 minutes. Reduce heat to 350°. Roast until an instant-read thermometer inserted into the thickest part of the thigh (puncturing bag with thermometer) registers 160°, about 1 1/2 hours longer. Cut top of bag open, being careful of steam and juices, and pull back over turkey. Roast turkey until breast is deeply browned but not burned and a thermometer inserted into thigh registers 165°, 15–30 minutes longer.
Transfer to a platter. Let rest for at least 20 minutes before carving.
Meanwhile, strain juices into a large saucepan. Spoon fat from surface. Simmer over medium heat until sauce is reduced to 3 1/2 cups, about 20 minutes. Add a little corn starch for thickness. Carve turkey. Garnish with cilantro and serve with gravy with side of basmati rice, or raita!