Preheat oven to 400°.
Place fennel seeds in a clean spice or coffee grinder; pulse until coarsely ground. Combine fennel, 1/2 teaspoon freshly ground black pepper, salt, and minced garlic in a small bowl; rub evenly over roast. Spray roast lightly with cooking spray. Place roast on the rack of a shallow roasting pan coated with cooking spray. Pour 2 cups broth into pan; place rack in pan. Bake at 400° for 30 minutes. Reduce oven temperature to 350° (do not remove roast from oven); bake an additional 40 minutes or until a thermometer registers 155°. Remove roast from pan; let stand, uncovered, 10 minutes before carving. Slice vertically between each rib bone.
Place a zip-top plastic bag inside a 2-cup glass measure. Pour drippings into bag; let stand 10 minutes (fat will rise to the top). Seal bag; carefully snip off 1 bottom corner of bag. Drain drippings into pan, stopping before fat layer reaches opening; discard fat. Add apple juice to pan. Combine remaining 1 cup broth and flour, stirring with a whisk. Add flour mixture to pan. Bring to a boil over medium-high heat, stirring constantly with a whisk. Boil 1 minute or until thickened, stirring constantly. Remove from heat; stir in remaining 1/4 teaspoon black pepper. Serve with pork.