Dissolve the yeast in a large bowl with warm water (not boiling!). Let it rest for a few minutes to reactivate the yeast, particularly if you use dry granular yeast.
Add sugar, oil, salt, and eggs to the bowl, then mix everything together; now add the flour, but slowly, two cups at a time, because it is not said that you will want to use it all. You will use about 2 kg, but perhaps even a little less, depending on weather conditions, and many other unpredictable factors.
When the dough becomes compact and no longer sticks to your hands, knead it well on a floured surface for ten minutes, then transfer it to a lightly greased bowl and let it rise for at least one hour (even two, if you wish) covered with a damp cloth until it doubles.
Once the mixture is well leavened, shape it (and if you do the hafrashat – I am talking to Jewish readers! – remember to take the part of dough required!). A simple braid with three rolls, like braided hair, is easily accomplished, looks great, and with this mixture if you can make 8.
Put the bread braids on baking pans covered with parchment paper, allow them to leaven for another half an hour.
Once fully leavened, brush the challot with 2 yolks diluted in a little water, and sprinkle with sesame or poppy seeds, then bake in a preheated oven at 200°.
Cook the challot at 200° for about 10 minutes, then reduce the temperature to 180° and bake for another 20 minutes.
The baking time depends on the oven (about 25/30 minutes, usually), but you will quickly notice if the challah is cooked: the surface will turn a nice color, between brown and golden, releasing a sweet aroma that would be noticed by even the most careless cooks ...