Mix the yeast, sugar, and flour.
Add the water, then add the vinegar and oil, and just before you finish mixing – add the salt.
Knead the dough for 10 minutes.
Allow the dough to rest for half an hour, covered.
Knead again for a few minutes.
Cover the dough with saran wrap, plus an extra cover, and leave it until it has doubled in volume (up to an hour).
After braiding the loaves, spray them with water and sprinkle them with sesame or poppy seed.
Place on a baking pan. Allow to rise again until the loaves have doubled in volume.
Bake in a pre-heated oven at 200C for 20 minutes, and spray the loaves twice more with water while they are baking.
If you prefer dark brown Challahs, brush the unbaked loaves with an egg wash instead of water.