Unroll roast; butterfly it by making a lengthwise cut almost through the roast, then spreading it out to lie flat. Pierce meat on all sides with the tines of a fork.
For marinade, combine thawed orange juice concentrate, lime peel, lime juice, oil, garlic, oregano, pepper, and salt.
Place meat in a plastic bag in a shallow dish. Pour marinade over the meat, coating all surfaces. Seal bag and refrigerate meat and marinade for at least 4 hours or overnight, turning meat and bag once.
Remove the meat from the bag, reserving the marinade. Reroll and tie the roast; place on a rack in a roasting pan. Insert a meat thermometer. Roast, uncovered, in a 325 degree F oven for 2-3/4 to 3-1/2 hours or until the meat thermometer registers 165 degrees F, basting frequently with reserved marinade during the first 2 hours of cooking time.
Remove from oven. Let roast stand for 10 minutes before slicing. Makes 10 main-dish servings.
Beans and Rice
In a saucepan cook 1/2 cup chopped onion, 1/2 cup chopped sweet green pepper, 2 cloves minced garlic, 2 teaspoons ground cumin, 1 teaspoon chili powder, and 1/2 teaspoon salt in 1 tablespoon hot oil for 2 minutes. Slowly add 2-1/2 cups water; bring to boiling. Stir in 1 cup rice. Transfer to a 2-quart casserole. Cover; bake in a 325 degrees F. oven 30 minutes. Pour 2 rinsed and drained 15-ounce cans black beans over rice. Do not stir. Return to oven. Cover; bake 5 to 10 minutes more or until rice is tender and liquid is absorbed. Gently stir in beans. Garnish with chopped tomatoes and sliced green onions. Makes 10 side-dish servings.