
Trim fat from the roast. In a small bowl, combine oregano, lemon peel, garlic and salt. Sprinkle evenly over sides of lamb; rub lightly with fingers. Place lamb into slow cooker. Sprinkle with lemon juice.
Cover and cook, on low setting, for 8-10 hours.
Remove lamb from cooker. Remove meat from bones; discard bones and fat. Chop meat a set aside. Skim fat from juices. Add spinach to cooking juices in cooker, stirring until spinach is wilted. Add cooked orzo, feta and lamb; stir to combine.