For making white sauce, take a small sized onion and insert 5 to 6 cloves into onion.Boil clove inserted onion and a small piece of bay leaf in milk. Onion and bay leaf will infuse a different aromatic taste to the white sauce.Bring the milk to boil over medium flame.In a pan melt butter.Add all purpose flour and stir fry over medium flame. Make sure that flour’s color doesn’t changes. Keep on stirring for 2 to 3 minutes.Remove onion and bay leaf from milk and add milk to the pan and keep on stirring. To avoid formation of lumps add milk in small portion and stir and repeat this process. Do not add milk to flour in one go.Bring the flour and milk mixture to boil, lower the flame.Add oregano (optional), black pepper and salt. I case you are using salted butter, keep the amount of salt low. I have used 2 pinches of salt.Mix well.Let it boil.White sauce is ready to use.