Step 1: Add the butter or oil to a skillet, heat and sauté the vegetable just a little to soften. Stir in the seasonings and remove from heat.
Step 2: Place the roast in a large roasting pan fat side up. Using a sharp butcher's knife, make a dozen or so slits downwards into the meat and to about 1/2-inch from the bottom. Do not cut all the way through.
Step 3: Use a small spoon to fill each pocket with the sautéed vegetable mixture. Rub the remaining mixture over the top of the roast.
Step 4: Bake uncovered in a 300 degree F. oven for about 3 hours for medium doneness or until a meat thermometer registers 160 degrees F or cook to 140 for a rarer roast.
Step 5: Remove from oven, rest for about 10 minutes and serve with the pan drippings or use the liquid to make a thin gravy.