Thank you all for nice comments
I'm sorry, but there will be no tutorial because i don't know how i did to get this result !! I took much time, pinning it myself, sewing, screaming, unstitching, giving up, taking some chocolate, trying again to fit those f**** pants, sewing, screaming... and so on.
I have no idea of the shape of the "pattern"....
But I'm making another pants (yeah, i'm masochist) but with a pattern, maybe i'll write a tute for this one