Saute ham and onion in olive oil. Add eggs and scramble. In small pan, heat butter and whisk in flour. Slowly add milk while whisking. Heat until thickened and bubbly. Salt and pepper to taste. Heat tortillas on a griddle until soft and pliable, but do not allow to harden. Divide the egg mixture into three tortillas and roll. Pour the white sauce over and top with cheese. Serve with salsa on the side.