Meanwhile, in 1-quart saucepan, melt butter over low heat. Be careful not to let butter burn or it will taste bitter. Stir in pecans. Heat, stirring constantly, until butter is golden brown. (If bottom of saucepan is dark, it may be difficult to see the difference between brown butter and burnt butter. Try spooning a little of the butter onto a white plate to see the color more clearly.) Immediately remove from heat. Pour butter mixture over beans; toss to coat. Sprinkle with lemon peel.