Cut asparagus into 2-inch pieces. Bring two cups water to a boil over high heat. Add asparagus, reduce heat and simmer until crisp-tender, about 5 minutes. Drain. In same saucepan, combine olive oil, lemon peel and lemon juice. Cook over medium heat for about 2 minutes. Toss with warm asparagus. Serve warm. Garnish with lemon slices.