PLACE potatoes, parsnips and 1 tsp. of the salt in large saucepan. Add enough water to cover ingredients; cover pan. Bring to boil on high heat. Uncover; reduce heat to medium. Simmer 15 minutes or until potatoes are tender.
DRAIN potatoes and parsnips; return to saucepan. Add sour cream and butter. Mash lightly, leaving some of the potato and parsnip pieces in chunks.
SEASON with pepper and remaining 3/4 tsp. salt.