Cook beans in boiling water (not too long or they'll get soggy!) for up to 5 minutes, or until crisp-tender. Drain and rinse with cold water.
Combine the tomato, vinegar, olive oil, salt and pepper in a bowl. Evenly divide the beans (either whole or precut) among 8 plates. Spoon 1/4 cup tomato mixture over the beans. Sprinkle with 1 tablespoon sliced basil and 1 tablespoon crumbled feta.