Preheat oven to 350°.
Arrange bread cubes in a single layer on a baking sheet. Bake at 350° for 15 minutes or until toasted.
Combine croutons, arugula, fennel, and onion in a large bowl. Combine water, lemon juice, and salt; stir well. Drizzle over salad; toss gently to coat. Spoon salad onto plates; top with cheese, and sprinkle with pepper.
Note: To shave Parmesan cheese, pull a swivel-blade peeler across the flat side of the cheese.