In a large bowl, combine the rinsed and drained chickpeas and black beans.
In a small bowl, whisk together the olive oil, red wine vinegar, dried oregano, salt, and black pepper.
Pour the dressing over the beans and toss to coat evenly.
Add the thinly sliced red onion, crumbled feta cheese, and chopped fresh parsley to the bowl.
Gently toss all ingredients together until well combined.
Cover the bowl and refrigerate for at least 30 minutes to allow the flavors to meld. For best results, chill for a few hours or overnight.
Serve cold or at room temperature.
