With a sharp paring knife pierce the roast at random intervals and insert some garlic in each slit. Preheat oven to 350 degrees.
In a casserole or deep roasting pan melt butter in oil. Brown pork loin on all sides and remove. In same casserole, in remaining fat, add the carrot and onion, cover and cook until soft, about 5 minutes. (If they begin to stick, add some white wine.)
When soft, bury pork in vegetables, add remaining white wine, season with salt and pepper and bake for 1 and 1/2 to 2 hours or until tender.
Remove, let rest for 10 minutes before carving. Slice half for one dinner and place remaining portion in refrigerator.