1. For chipotle marinade, heat 2 tablespoons oil in small saucepan over medium-high. Add garlic and onions; cook until lightly caramelized, about 5 minutes. Add chipotle chiles, honey, oregano, cumin and paprika; cook and stir, scraping cooked bits from bottom of pan.
2. Remove marinade from heat and pour into blender. Add salt and process until smooth, set aside to cool. Place 3/4 of marinade in medium bowl; reserve the rest in a small bowl.
3. Place loin into marinade making sure pork is fully covered. Refrigerate for at least 30 minutes.
4. Heat oven to 350°F. Heat remaining 1 tablespoon oil in large skillet. Sear pork on all sides, approximately 5 minutes on each side. Place pork on baking sheet and roast in oven until internal temperature reaches 145°F to 160°F, about 20 to 30 minutes. Let stand 10 minutes before slicing to serve. Serve topped with reserved marinade; Mexican rice and avocado salad on the side.