meteor event to get this.userId just after creating a new user

Question

I want to map the id of a user to a name.

Eg: {A: eSQyPRis4QQfQ5vQT, B: 84m9PFZZj79G9uH8M}.

So when creating a new user, I want to map his id to a variable. I imagine the code might be like,

Accounts.justAfterCreatedAUser({
    values['A'] = this.userId;
})

But I couldn't find anything similar. How can I achieve this?