Place your grill pan or basket inside your grill, and preheat the grill to 450°F.
Bring a large pot of water to a boil, then add the trimmed green beans to the pot. Boil for 3-4 minutes, until blanched and bright green. Drain and place in a large bowl. Place the halved garlic cloves in the bowl as well.
In a small bowl, combine the garlic powder, onion powder, lemon juice, oil, and salt. Stir to combine.
Pour the garlic mixture over the green beans and fresh garlic and toss to coat.
Once preheated, place the green beans and garlic cloves inside the grill basket or pan. Close the grill, and cook for 15-20 minutes, until the green beans begin to blister and char. Toss the green beans every 5 minutes to ensure even cooking.