How can I ask out my ex's friend?

We broke up very amicably after a short relationship and she since moved away but I do think I like one of her friends and would like to ask her out but don't know a procedure. Do I ask the ex if I can contact, do I ask the ex if she would recommend an activity partner in the area for me to do stuff with, do I go ahead and just email to see if she wants to get together? Any help is appreciated.