Boston Bean Salad

• 2 torn curly endive
• 475 gr navy beans
• 475 gr beans (red)
• 475 gr black beans
• 120 ml vinegar or more
• 60 ml molasses
• 60 gr thinly green onion (sliced)
• 5 ml dijon-style mustard
• 1 gr pepper
• 2 slices stalks celery