Preheat oven to 450 degrees F. Place the pork into a large, oiled roasting pan. Roast for 15 minutes. Turn and roast 15 minutes longer. Arrange the garlic, chilies, fennel wedges, and chopped onions around the roast, and top with tomatoes and basil. Roast for about 30 minutes, or until an instant-read thermometer registers 160 degrees F. Slice the pork and serve with the roasted vegetables.