Drain, rinse and drain white beans. Place in medium heavy saucepan and add onion halves (with cloves), bay leaf, and enough water to cover by an inch. Bring to the boil, reduce to barely a simmer, cover and cook 20 minutes. Add salt and pepper, and a little more water if none is visible when you tilt the pan, and cook another 2030 minutes until beans are creamy inside but still intact. Drain and remove onions and bay leaf. Let cool.

Place white beans in a large bowl with olive, peppers, cucumbers, scallions and tomatoes. Make vinaigrette by placing vinegar in a small bowl and slowly drizzling in olive oil while whisking to form an emulsion. Pour vinaigrette over beans and vegetables, add parsley, and stir well. Taste and adjust seasoning if necessary. Serve at room temperature.