In a large bowl, whisk together the shallot, lemon juice, orange juice, vinegar and mustard.
Drizzle in the olive oil and whisk vigorously to combine.
Season with salt and pepper.
Add the beans and toss until well coated in the dressing.
Rinse the red onion slices under cold water, drain, and toss into the bean mixture.
Add the fennel, the celery and celery leaves, and the dill to the salad bowl and toss to combine.
Season with more salt and pepper and serve.
