Toss the green beans into a large pot of boiling salted water and cook until bright green in color and crisp-tender, about 5 minutes. Drain the beans and shock in a large bowl of ice water to stop the cooking. Drain the beans again and pat dry.

Cook the bacon in a large, heavy saute pan until crisp, about 5 minutes. Remove the bacon to a paper towel-lined plate to drain. Spoon off the excess bacon grease, leaving 2 tablespoons in the pan.

Add the onion to the pan and saute until soft and very tender, 4 to 5 minutes. Sprinkle in the garlic and saute until just fragrant, about 1 more minute. Add green beans and toss with bacon and onion. Cook and toss 5minutes, or until heated through. Season with salt and pepper.