Meanwhile, scrub potatoes with a vegetable brush under cold running water. Peel. Cut into 1-inch pieces. Place potatoes in medium saucepan and enough cold water to cover. Over medium high heat, bring to boiling. Reduce heat to medium. Cover and simmer until potatoes are vey tender, about 12 to15 minutes. Drain. Return potatoes to saucepan and add tomato mixture milk, butter, salt and pepper. Mash until smooth.