Snap off any stems that may still be attached to the individual bean pods and rinse the green beans in cold water. Pat them dry.
Prepare all other ingredients before starting to cook.
Prepare the grill to a two-temperature zone and make sure the hot zone is set to hot temperature, about 425°-450°. You will be cooking over cooler side or you’ll burn butter and garlic.
Set a cast iron skillet over indirect heat once the grill is preheated and let the skillet preheat for a few minutes.
Add butter to the skillet and once it starts to melt, add minced garlic and squeezed lemon juice.
When butter is melted, toss in green beans and season with salt, pepper, and garlic powder. Use long metal tongs to toss the green beans with butter and seasoning. (It’s best to use long tongs to keep your hands away from the heat and preferably ones coated in silicone so you don’t scratch the skillet.)
Cook grill beans, stirring them often, until it’s reached desired tenderness. This will take somewhere between 10 and 15 minutes.