For filling: Cook potatoes in boiling salted water until tender, about 20 minutes. Drain well. Return saucepan to heat for about 1 minute to remove excess moisture, shaking pan to prevent scorching. Mash potatoes with a potato masher. (If done in the processor, they become gluey.)

Combine potatoes with onions, oil, eggs and seasonings. Mix well.

Assembly: Divide dough into 4 pieces. Working with one piece at a time on a floured surface, coat lightly on all sides with a little flour and pat into a rectangle. Roll as thin as possible into a large rectangle.

Place a row of filling about 2 inches wide along longer side of rectangle, about 1 inch from edge. Roll up into a long roll. Using the edge of your hand, press down on roll and, with a sawing motion, cut through dough. Repeat every 2 inches. Turn knishes on end, pressing cut edge in slightly. Repeat with remaining dough and filling.

Bake on sprayed baking sheet in preheated 350° F oven about 35 minutes until golden.

Variation: To make miniature knishes, roll dough into a 6 x 18-inch rectangle. Place a narrow band of filling (about 1 inch wide) along longer side of rectangle, about 1 inch from edge. Roll up into a long, narrow roll. Cut with the edge of your hand into 1-inch pieces. Seal ends. Bake for 20 to 25 minutes, until golden. Excellent for hors d'oeuvres.