Trim bases from fennel bulbs; cut bulbs into quarters.
Toss together fennel, potato, and oil in a 15- x 10-inch jellyroll pan; sprinkle with salt.
Bake at 425° for 30 minutes. Add green beans, and toss gently. Bake 10 to 15 more minutes or until vegetables are lightly browned. Sprinkle with pepper, and serve hot or at room temperature.
* 1 teaspoon salt may be substituted.