In an 8x8 glass dish (or something similarly sized) lay a large piece of foil (large enough to wrap the veggies and meat.)
Place the vegetables on top of the foil, followed by the turkey loin. Rub the seasoning (I use Tony's) on top of the meat. Lay the butter on top.
Wrap the packet completely with the foil. Use an additional piece of foil, and wrap it again. Try to get both seams on top.
Bake in a 350*F oven for an hour and 20 minutes, or until the meat reaches 160* and the vegetables are tender. I just stick a thermometer through the foil to keep the moisture inches Let it rest for 10 minutes or so before serving.