Bring a large stockpot of water to a boil. Cook the string beans for 2 minutes, then drain and set aside.
Heat a large high-sided skillet over medium heat. Add the olive oil, 2 tablespoons of the garlic and the string beans and stir. Add the salt and pepper and mix again, then add the remaining 1 tablespoon garlic and stir to make sure the string beans are coated. Cook until tender, 5 minutes, and then serve.