Feel free to prepare the barley tea using your preferred method, whether by simmering, steeping in hot water or cold brewing. You can find instructions on how to make barley tea with various methods here: how to prepare barley tea.
You can adjust the amount of milk to suit your taste.
This recipe works specially good when the barley tea tastes slightly too strong for your taste: adding the milk balances it out like magic!
Skip the sugar for a lighter version. I personally enjoy using this homemade vanilla honey.