Combine the pesto, basil, and olive oil in a small processor until well blended. Spread this mixture on the pork loin and cover and refrigerate for 4 hours, even overnight if you have the time.

Combine the fennel, onions, and peppers in a large bowl. Toss with the Vinaigrette, cover and marinate in the refrigerator along with the pork. 

When you are ready to roast. preheat the oven to 375 degrees. Spray a baking dish with cooking spray. Add the vegetables and about half of the salad dressing. Roast for 10 minutes or until the vegetables begin to soften.

Place the roast on top of the vegetables and return the dish to the oven. Roast for about 40 minutes to an internal temperature of 145 degrees. Allow to rest before slicing.

Serve the roast and vegetables on their own or add a starch of your choice. Polenta is very nice.