Combine the rub ingredients and mix well. Separate the roast pieces by un-tying butchers twine and apply the rub onto surfaces of the roast.
For the stuffing, melt the butter in a large skillet over low heat. Add the chopped onion, garlic and mushrooms; cook over medium- high heat for 3-5 minutes, stirring occasionally. In a large bowl combine the cubed stuffing, parsley, lemon pepper, tarragon, egg, mead and lemon juice. Add the cooked vegetables and mix gently, ensuring that it is well moistened. If necessary, add more mead! Carefully pack stuffing on one piece of roast, place the second piece on top and re-tie.
Place roast on a rack in a shallow roasting pan. Insert a meat thermometer in the thickest part of the roast. Place a large piece of aluminum foil loosely over the roast, making a slit to expose the meat thermometer. Roast at 325°F for 20-25 min per pound (163°C for 40-50 min per kg.) or until the thermometer reaches 155-160°F (68-71°C). Combine the honey and lemon juice (basting sauce); brush over roast and stuffing during the last 20 min. of cooking time. Let the roast stand 10 min. before carving. Garnish if desired.