MIX dressing, chipotle pepper puree and sugar. Reserve 1/4 cup of the dressing mixture; refrigerate until ready to use. Pour remaining dressing mixture over meat in shallow dish. Refrigerate several hours or overnight to marinate.
PREHEAT oven to 425°F. Remove meat from marinade; discard marinade. Place meat in shallow baking dish.
BAKE 25 minutes or until meat thermometer inserted in center registers 160°F, brushing with the reserved 1/4 cup dressing mixture after 15 minutes. Meanwhile, combine remaining ingredients. Cut meat into 1/2-inch-thick slices. Serve with the orange salsa.