Prepare the Ingredients: Begin by thoroughly washing and dicing the celery, red bell pepper, cucumber, and red onion. Ensure all pieces are uniformly cut to provide a consistent texture.
Combine the Crab and Vegetables: In a large mixing bowl, add the crab meat, celery, red bell pepper, cucumber, and red onion. Mix gently to combine.
Make the Dressing: In a separate bowl, whisk together the mayonnaise, lemon juice, and Dijon mustard until smooth. Season the dish with salt and pepper according to your preference.
Mix Everything Together: Pour the dressing over the crab and vegetable mixture. Gently fold until everything is evenly coated with the creamy dressing.
Chill and Serve: Place the salad in the refrigerator for a minimum of 30 minutes, allowing the flavors to blend together. For an extra touch, garnish with fresh parsley before serving, if desired. Serve chilled on a platter or in individual bowls.