Does anyone have a good mustardy lamb cooked slowly recipe?

[Howaboutthisone]

I'm really liking the sound of Jamie's 15 minute meals mustard lamb with Irish mash. The only thing is that I'm not a big fan of lamb usually unless it's been slow cooked and is lovely and falling apart. I'm not sure how to get the mustard flavour and the slow cooked to work as I'm pretty clueless.
Any ideas would be very gratefully received.

[JiltedJohnsJulie]

Just marking my place