left outer join in lambda/method syntax in Linq

Possible Duplicate:
How do you perform a left outer join using linq extension methods

I can't find a left outer join example of Linq lambda (with extension methods), at least, not a clear one.

Let's say I have the following table:

Parent
{
    PID     // PK
}

Child
{
    CID     // PK
    PID     // FK
    Text
}

I want to join Parent with Child, and for every child missing, I want the default value for Text to be "[[Empty]]". How can I do this with linq lambda syntax?

I currently have the following:

var source = lParent.GroupJoin(
    lChild,
    p => p.PID,
    c => c.PID,
    (p, g) =>
        new // ParentChildJoined
        {
            PID = p.PID;
            // How do I add child values here?
        });