Place all ingredients except the salt into a large bowl. Begin kneading. When a ball of dough is formed, add the salt. Knead the dough for approximately 10 minutes, until the douh is smooth and soft, but not sticky.
Brush the dough and bowl with a bit of oil, cover the bowl with plastic wrap or a clean kitchen towel, and let the dough rise in a warm place for approximately 1 hout, until the dough doubles in volume.
After the dough has risen, knead it for a few minutes. Roll pieces of dough into strands to be braided.
To make more airy challahs, roll out each strand into strips, ca. 1/4 inch (1/2 cm) thick. Roll each strip jellyroll fashion to from a tube and use these to braid the challahs.
Place the challahs on a baking sheet to rise. Brush with beaten egg and sprinkle with sesame or poppy seeds. COver and let rise again in a warm place for ca. 40 minutes. In the meantime, preheat oven to 350 F (180 C).
Bake for approximately 30 minutes, until the challahs turn golden brown. Remove the challahs from the oven and from the pan and cool on a wire rack.