In a large a bowl add 1 1/2 cup flour, sugar, yeast, and salt mix together. Heat the milk and water until warm, (microwave works nicely for this). Add the milk/water,olive oil, and onion to the flour mixture. Mix in with a wooden spoon or by hand.
Gradually add the rest of the flour (just until the dough is slightly sticky). Kneading the dough until it is smooth. Grease the bottom of the bowl, flip the bread to coat both sides.
Cover and let rise for 45 minutes to an hour or until double in size.
Once the dough is double in size divide into 12 pieces. Form into balls and place on a greased baking sheet, with you finger pat down to form a circle. Place in a warm place for about 30 minutes so that the buns are raised and about double in size.
Preheat the oven to 375 degrees F. Take the egg and water and beat together. Just before the buns go into the oven brush them with the egg mixture.
Once the buns have raised for 30 minutes place in the preheated oven and bake for 12 to 15 minutes or until golden brown.
Serve warm.