Wash and trim green beans and place them in a microwave-safe dish with 2 tablespoons filtered water in the bottom of the bowl. Steam for 1 minute, remove from microwave and toss, then steam for 1 minute more. Drain and set aside.
Heat oil or butter in a cast iron skillet over medium heat until hot. Add green beans, garlic and rosemary and cook for 2 minutes, using tongs to turn them continuously until the garlic is fragrant, browned and crispy.
Remove beans from heat and transfer to a serving dish. Finish with a squeeze of fresh lemon and serve!