Add the white beans, lemon juice, olive oil, minced garlic, dried oregano, salt, and black pepper to a large bowl. Stir gently and let the beans marinate for 15 to 20 minutes.
Dice the cucumber, halve the cherry tomatoes, thinly slice the red onion, and chop the parsley while the beans sit.
Add the cucumber, cherry tomatoes, red onion, olives, and parsley to the marinated beans. Toss gently until everything is well coated.
Fold in the crumbled feta carefully so it keeps its texture.
Serve right away or chill for 20 to 30 minutes before serving for even better flavor.
