Place the flour in a large mixing bowl and make a well in the center.

Pour 1/4 cup warm water in the well. Add the yeast and sugar and stir gently to dissolve. Let sit for five to 10 minutes until it is bubbling.

Add 1/4 cup oil, mashed potato, and salt. With a wooden spoon (or better yet, your hands), start to mix the flour into the yeast mixture in the well. Gradually add more of the remaining two cups warm water as needed to moisten the flour (being careful not to add too much — the dough should remain firm and you probably will not need to use all two cups!), while continuing to mix.

Remove the dough from the bowl and put on a floured breadboard (or a clean counter top). Knead by hand (press dough hard with the palm of your hand, fold the dough over, and repeat) until all the flour is incorporated and the dough is well-blended and smooth.

Wash and dry the mixing bowl and grease lightly with oil. Return the dough to the bowl, cover with a slightly damp kitchen towel, and place in a warm spot (such as in an oven that has been warmed on low, then turned off). Let it rise until doubled in size, one to two hours.

Punch down the dough in the bowl. Return to the floured breadboard (or counter top) and knead until smooth.

Lightly oil a baking sheet. Cut the dough into three equal parts and roll each part into a rope of equal length. Line up the three ropes in a parallel row. Pinch the ends together at one end. Cross the left-hand rope over the middle rope (the left-hand rope now moves to the middle position). Cross the right-hand rope over the middle rope. Continue crossing left- and right-hand ropes until you reach the end of the ropes. Pinch the ends together and tuck under. Place on baking sheet.

Cover the loaves with the damp kitchen towel. Return the baking sheet to the warm spot and let the dough rise again until doubled in size, one to one and a half hours.

Preheat oven to 350 degrees Fahrenheit. Brush the top of the bread with the beaten egg white and sprinkle generously with the poppy seeds. Bake for 30–40 minutes, or until the top is golden brown and when you tap the bottom it makes a hollow sound. Place on a wire rack to cool.