Rinse and drain the chickpeas in a colander. Peel and finely slice the red onion. Wash the cucumber and parsley. Dice the cucumber and chop the parsley.
In a large bowl, mix the chickpeas, red onion, cucumber, crumbled feta, and parsley.
Prepare the dressing: In a small bowl, mix the olive oil and lemon juice. Season with salt and pepper. Whisk until you have a homogeneous emulsion.
Drizzle the salad with the dressing and gently toss to coat all the ingredients.
Let the salad sit in the refrigerator for at least 30 minutes before serving to allow the flavors to meld.