Bring a large pot of water to a boil. Add 1 tablespoon salt and the green beans and cook until tender, 4 to 6 minutes.
Meanwhile, heat the oil in a skillet over medium heat. Add the garlic and cook for 1 minute. Add the tomatoes, 1/2 teaspoon salt, and 1/8 teaspoon pepper and cook, stirring occasionally, for 3 minutes.
Drain the green beans and add them to the skillet, along with the lemon juice. Toss to combine. Transfer to a serving dish.