Combine flour and oil and cook over medium heat, stirring constantly, to make a roux. Add hot water gradually, stirring to blend. Place ham in roasting pan. Surround roast with onions, sprinkling some over top. Salt and pepper liberally. Pour roux over roast. Cover pan and bake one hour at 350 degrees. Make a sauce with remaining ingredients. Pour sauce over roast and bake three more hours, uncovered for the last hour. Slice and serve with gravy over rice. To decrease wild taste of deer, marinate in buttermilk overnight.