1 Bring Marinade Ingredients -- Wine, Vinegar, Water, Peppercorns, Juniper, Mustard, Cloves, Bay Leaves, Thyme, Celery, Carrots And Onion -- To A Boil And Turn Off The Heat. Allow To Cool. Submerge The Venison In The Marinade And Let It Sit In The Fridge For At Least 24 Hours, And Up To 5 Days. Three Days Is A Good Length Of Time. When You Are Ready To Cook, Take The Roast Out Of The Marinade And Salt It Well. Set It Aside For 15-20 Minutes Or So. 2 Preheat The Oven To 275 Degrees. Actually, 225 Is A Better Temperature, But The Roast Can Take Up To 8 Hours To Properly Cook Then; This Is What I Do At Home On Weekends. At 275 Degrees, The Roast Will Probably Take About 5 Hours To Cook. You Can Go Up To 300 Degrees