Cook cauliflower in boiling water to cover 5 to 6 minutes or until crisp-tender. Plunge into ice water to stop the cooking process; drain and set aside.
Heat 1/4 cup olive oil in a large skillet over medium-high heat until hot. Add celery and onion; sauté 3 minutes or until almost tender. Add garlic; sauté 30 seconds. Stir in vinegar and honey, stirring to dissolve honey.
Combine cauliflower and sautéed vegetables in a large bowl. Add remaining 1/4 cup olive oil, beans, and next 5 ingredients; stir well to combine. Serve warm or at room temperature. Garnish, if desired.