Preheat oven to 350°. Unroll lamb, if necessary. Rub 1 lemon half on all sides of lamb, squeezing juice from lemon. Stir together oregano, salt, and pepper; rub on lamb. Roll up lamb, and tie with kitchen string.
Place lamb on a lightly greased rack in a roasting pan. Separate garlic cloves (do not peel), and place around roast. Drizzle olive oil over lamb and garlic cloves.
Squeeze juice from remaining 1 1/2 lemons into a bowl. Stir together juice and chicken broth; pour into roasting pan.
Bake at 350° for 2 hours to 2 hours and 15 minutes or until a meat thermometer inserted into thickest portion registers 140° (medium) or to desired degree of doneness. Remove lamb from pan; cover with aluminum foil, and let stand 10 minutes before slicing. Garnish, if desired.
TRY THIS TWIST!
Roasted Boston Butt: Substitute 1 (5-lb.) bone-in pork shoulder roast (Boston butt) for lamb. Rub lemon and oregano mixture over roast as directed. (Do not tie up roast.) Proceed as directed, increasing bake time to 3 to 3 1/2 hours or until fork-tender. Shred pork into large pieces using two forks, if desired. Hands-on time: 20 min. Total time: 3 hr., 30 min.