To make dough: Combine 1-1/2 cups flour, yeast, sugar, onions, salt and rosemary in a large bowl. Heat milk, potato flakes, water and oil until very warm (120º to 130ºF). Stir into dry ingredients. Stir in enough remaining flour to make soft dough. Knead on lightly floured surface until smooth and elastic, about 4 to 6 minutes. Cover; let rise 10 minutes.
Divide dough into 12 equal portions. Roll each piece into a 12-inch rope; tie a loose knot in the center of each rope. Place rolls, 2 inches apart, on greased baking sheet. Cover. Let rise in warm, draft-free place until doubled in size, about 20 to 40 minutes.
Brush tops of rolls with egg. If desired, sprinkle with sesame seed, poppy seed OR rosemary. Bake at 375º F for 15 to 20 minutes or until done. Remove from baking sheet; cool on wire rack.