Early in the day prepare the pork loin and marinade. Rinse pork loin to remove any unwanted smells and pat dry with paper toweling. Remove pork to a nonreactive container. Place the limes and lemons in a small microwave-safe bowl and microwave until the essential oils in the skin are released. Since these will be hot coming from the microwave, you will need to set them aside briefly, until they cool just enough to handle. Blend the garlic cloves and the garlic pepper seasoning in a blender, then while the blender is still running, squeeze the juice of the limes and lemons through the feed tube to make a paste. With the blender still running, add the oil in a thin stream. Rub the paste into the pork, cover and leave refrigerated for 2 hours.
Preheat oven to 350 degrees F. In a large saute pan with an oven safe handle, heat the oil and sear the pork loin on all sides. Roast covered in oven until fork tender, at least 45 minutes. Transfer pork to a utility platter and let rest in a warm place before slicing.
The pork can also be cooked on the grill. Heat grill to medium-high heat. Wrap pork in a foil pouch in which you have shaken 1 tablespoon flour, and cook over indirect heat (on the side of the grill opposite the direct heat source) for about 1 hour 45 minutes to 2 hours. Let pork rest before slicing.
While the pork is cooking, prepare the aioli. Add peaches, mayonnaise, and cilantro to a food processor and blend until smooth. Season with salt and white pepper, to taste.
Lay slices of pork loin on rolls and spoon peach aioli over. Garnish with cilantro sprigs.