Mix 2 cups of warm (under 90F) milk with 1 Tbsp of sugar, and 1/2 tsp of yeast and allow to sit for about 10 minutes.
Then, add 1 egg and 1 1/2 cups of flour and 1 tsp of salt. Place the whisk in the middle and slowly start to whisk the mixture into a smooth batter. If you try to keep your whisk only in the middle of the mixture and allow the flour naturally to come towards the middle to be whisked, you will have a smooth batter with no lumps. Lastly, add 2 tbsp of oil and whisk until smooth once more.
If you still ended up with flour lumps in the batter, pour the batter through a sieve to remove them.
Cover the mixture with a tea towel and set it into the oven with the light on (do not turn on the heat) or any other warm, draft-free place for about 45 minutes to 1 hour. During this time the mixture should form a foamy top. Stir the batter and preheat your skillet for cooking crepes.
Preheat an 8-inch skillet over medium heat until it's thoroughly heated and you can feel the hotness of the pan if you hover the palm of your hand about 2 inches above the skillet.
Pierce 1 tbsp of cold butter with a fork, then quickly grease the bottom of the pan with the butter.
Next, using a 1/4 cup measuring spoon pour the batter in the middle of the pan and swirl it to cover the bottom completely. Cook for several minutes until the top is no longer wet. Then, using a spatula carefully flip the crepe and cook on the other side for a couple more minutes. Transfer to a plate.
Continue cooking the crepes in this manner until all batter is used up. Do stir the batter throughout cooking so the flour doesn't settle in the middle.
To store the crepes - Allow the crepes to cool completely, then cover with plastic wrap and refrigerate until ready to serve.
When ready to serve either bring them to room temperature beforehand, or pop the plate with the crepes into the microwave.