Place pork in a large self-sealing plastic bag set in a shallow dish. Add ale, garlic, lemon peel, dried rosemary, salt and pepper. Seal bag. Turn to coat. Refrigerate 4 hours or overnight, turning bag occasionally.

Place potatoes and carrots in bottom of 5- to 6-quart slow cooker. Transfer pork ribs to bed of carrots and potatoes. Pour ale mixture over all. Cover and cook on low-heat setting 8 to 9 hours or on high-heat setting 4 to 4-1/2 hours.

Remove pork and vegetables from cooker. Cover; keep warm. Pour cooking juices through fine mesh sieve set over a heat-proof bowl to strain. Measure 2 cups of cooking juices, adding water to make 2 cups, if necessary. Stir together water and cornstarch in medium saucepan. Add 2 cups strained juices. Cook and stir until thickened and bubbly. Cook and stir 2 minutes more. Serve sauce with meat, vegetables, and radishes. Garnish with fresh rosemary and lemon peel. Makes 4 to 6 servings.