Cook pasta according to package directions. Drain, rinse with cold water, and drain thoroughly.
In a large bowl, combine cooled pasta, red onion, cucumber, tomatoes, feta, and beans.
To a small jar or bowl, add vinegar, olive oil, oregano and salt and pepper. Cover and shake until combined, or whisk if in a bowl.
Pour dressing over salad and stir until everything is well combined. Keep in fridge until ready to serve, up to a day. Stir again just prior to serving.
Notes
If desired, soak chopped onion in ice water for at least 10 minutes. This takes away the bite and makes it much more mild.
Optional: Add kalamata olives to salad.
If using fresh oregano, increase amount to 3 tablespoons.
Other types of pasta may be substituted, including whole wheat and gluten-free.