One of my friends is suffering with asthma. She tried a lot of treatments and medicines, but she didn't get any effective change. At her friend's suggestion, she visited a doctor and he recommended breathing exercises. She started them and now it is a daily routine for her. Her life has changed dramatically, and asthma no longer bothers her.
Your post is inappropriate for this forum. There's no cure for asthma. Maybe you, as a non-asthmatic and a non-healthcare professional, can show the asthma community some respect by changing your post to "Dysfunctional Breathing and how it can be helped by breathing exercises" and drop the suggestion that your friend's asthma has been cured. Can you even share what asthma phenotype your friend has, their daily medication regime, how they were diagnosed, tests etc? Maybe you were trying to be helpful, unfortunately your post doesn't read that way and it demonstrates your third hand ignorance of a very complex disease, which many desperately try to manage despite their best efforts. If they could cure it by just breathing exercises do you not think we would have cracked that one? Sheez.
FYI dysfunctional breathing can be mistaken for asthma, but it isn't asthma. Asthmatics can benefit from breathing exercises but they cannot cure asthma or the root causes that cause the inflammation.
If you're still not convinced, try wearing a plastic bag over your head for a day so you can experience the full effects of asthma yourself and see if breathing exercises do it for you, while wearing the plastic bag of course. "How to cure asthma", are you for real?