Place potato in a medium saucepan and cover with water; bring to a boil. Reduce heat, and simmer 15 minutes or until tender; drain, reserving 1/4 cup liquid.
Melt margarine in a medium nonstick skillet over medium heat. Add fennel and onion; cook, stirring constantly, 12 minutes or until tender.
Combine potato, reserved potato liquid, fennel mixture, salt, and pepper in a medium bowl. Mash with a potato masher.
Oxmoor House Healthy Eating Collection
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