Lol,thanks for the replies.
I've been promised a recipie from the same place.
They knew exactly what I meant, but there was much shaking of heads.
'Chef just comes in and makes it, we dunno what he puts in it'.
And - 'we dunno, but you can't make it at home'!
Anyway, the deal is, I take a portion of my (modified muttley's base) in and chef gives me some tips, a recipie, and hopefully a sample

One comment stuck in my mind though, and I cant say whether it applies to the base or the finished dish:
'He has been cooking for 'Gori' for 20+ years, he just has the knack.
Gary