Favorite Chickpea Salad

2 cans (15 ounces each) chickpeas, rinsed and drained, or 3 cups cooked chickpeas

1 medium English cucumber, chopped

1 ½ cups chopped fresh flat-leaf parsley (about 1 bunch)

1 bunch green onion, chopped

½ cup chopped celery (about 2 ribs)

3 tablespoons extra-virgin olive oil

3 tablespoons lemon juice (from 1 to 1 ½ lemons), or more if needed

2 cloves garlic, pressed or minced

½ teaspoon fine salt

Freshly ground black pepper, to taste