Younger minds

I've been finding it difficult at work recently. I work currently work with someone who is completely immature, unable to work independently and completely emotional and irrational. I'm a Team Leader in my work place, so I have the responsibility of managing her on quite a few shifts per week. When she first started, I made her cry (unintentionally) by asking her to put a sandwich in the toaster three times (I work in a large chain cafe)... I didn't shout or raise my voice but she said that I pressured her and she didn't understand. Its been three months since this incident and yesterday was a busy shift. We had done double the sales we were expected so we were understaffed for the day. She had been frustrating me all morning and I was stressed at the amount of work I needed to do and wouldn't be getting any help for. I went to serve a customer and while I was serving she came up to me with two cambros of prepped veg with the wrong day dots (I put onions on cucumber and cucumbers on onions). She smirked and laughed at my mistake and because I was so worked up and stressed and told her 'thanks for pointing out my mistake, that helps doesn't it' and finished serving the customer and went outside to breath. When I came back two minutes later, I was told she was crying outside. I text my manager straight away to tell him what had happened and in turn he told me she had told him that she wanted to quit. I don't understand why she got so emotional when firstly it was me getting upset and secondly, I want to know if there is anything that can be done to right the situation properly? I know its something I should let go of and I did apologise for causing her to get upset... However, I'm finding it TOO difficult to work with her and I don't know what to do about that...

On one side of the coin, your responsibility of managing her means just that, manage her. Her responsibility (to you, to herself, your employer, the team and the customers) is to ensure she does the work to the best of her ability whether you need to direct her to do so or not. Your company's HR is paid to manage issues like you're experiencing and you need to report (written) accurately to them and to your manager. On the other side of the coin, you need to understand that, going by your post, and without being judgmental, she isn't suited for this type of role if she can't take directions from her TL without becoming upset about it. She needs to understand that to work in the service industry, you have to have the need to serve your customers quickly and efficiently for return business. She also needs to understand that if it's just going to be a job, without any care factor for the people (the customer) who ultimately pay her salary, then it'll be a short lived job. Finally, apologising to her is not going to help her because it becomes her satisfaction by you apologizing to her. You have basically apologised to her because of her immature behavior in the first place. Your reaction upset her when your main focus was the customer, as hers should be. Disruptive and self centered are two further words which come to mind to describe her. This girl may have or may have had personal problems at home which could explain her behavior, however, you need a team of people who can do the job without the hysterics.