Peel and halve potatoes; put in large saucepan with enough water to cover. Bring to boil; simmer, covered, 20 to 30 minutes, until fork-tender. Drain well; return to saucepan over low heat. Add butter; mash potatoes well. Stir in flour and salt. Gather mixture into a ball; turn onto lightly floured surface. Knead lightly until smooth. Divide dough in half. Roll out one half into an 8 in. (20 cm) circle, about 1/4 in. thick. Cut into quarters; set aside. Repeat with remaining dough. In large nonstick skillet, heat half the oil over medium-high heat. Cook dough quarters in batches, 2 minutes on each side or until golden brown, adding more oil as necessary. Serve warm.