Preheat a grill to medium-high heat (375 to 450°F).
Wash and trim the green beans. Pat them dry with a towel. In a bowl, mix the green beans with the olive oil, kosher salt and plenty of fresh ground black pepper.
Place the green beans directly on the grill grates and grill for about 4 to 5 minutes per side (8 to 10 minutes total), until charred and tender. (For a less charred result, you can cook them in grill basket for 12 to 14 minutes until tender.)
Remove the beans from the grill and spritz them with lemon juice from wedges. Taste and add a few more pinches of kosher salt, if needed.