Heat 1 teaspoon oil in a large skillet over medium-high heat.
Add green beans and cook, stirring often, until seared in spots, 2 to 3 minutes. Add water, cover, reduce heat to medium and cook, stirring occasionally, about 3 minutes for tender-crisp or 6 minutes for tender.
Push the beans to the side; add the remaining 1 teaspoon oil and garlic and cook until fragrant, about 30 seconds.
Add tomatoes, stir everything together and cook until the tomatoes begin to break down, 2 to 3 minutes.
Remove from heat; stir in vinegar, salt and pepper.