1 can (11 ounces) mandarin oranges, drained, optional
Cut roast in half. In a large skillet, brown roast in oil and butter on all sides.
Transfer to a 5-qt. slow cooker. Add the orange juice concentrate, water, garlic, salt and pepper. Cover and cook on low for 4-6 hours or until meat is tender.
For glaze, in a small saucepan, combine the brown sugar, vinegar, orange juice concentrate and garlic. Bring to a boil. Reduce heat; simmer, uncovered, for 3-5 minutes or until reduced to about 1/4 cup. Brush over roast. Garnish with oranges if desired.