In a small bowl, place yeast, 1 tsp sugar and lukewarm water. Allow to sit for around 10 minutes until it becomes foamy on top.
In a large bowl or stand mixer fitted with the whisk attachment, mix together 1½ cups flour, salt and sugar. After the water-yeast mixture has become foamy, add to flour mixture along with oil. Mix thoroughly.
Add another cup of flour and 2 eggs and mix until smooth. Switch to the dough hook attachment if you are using a stand mixer.
Add another 1½- 2 cups of flour, mix thoroughly, then remove from bowl and place on a floured surface if kneading by hand or switch to the dough hook for machine kneading.
Knead remaining ½ cup flour into dough, continuing to knead for around 5 minutes (or however long your hands will last). Place dough in a greased bowl and cover with plastic wrap. Allow to rise for at least 3 hours.
Preheat oven to 375 degrees F.
Cut dough into 2.5-3 oz pieces. Roll each piece into a rope and then form a knot by just tying it, tucking the under end underneath.
Allow challah rolls to rise another 20-25 minutes.
In a small bowl beat 1 large egg. Brush egg wash liberally over challah.
Bake for 18-20 minutes, or until golden. Remove from oven.