Fill a medium pot with 1 in. water, insert a steamer basket, and bring to a boil, covered. Put beans in steamer and cover. Steam until bright green and tender, 8 to 10 minutes. Drain.
Put beans on a serving plate. Drizzle with butter and lemon juice. Sprinkle with zest, salt, and walnuts.
Servings 0
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.