How to make a shooter's sandwich

Thanks to @hharrismusic on twitter for the link to this monstrous & gorgeous sandwich. Not for vegetarians nor the impatient. Thankfully, I’m neither.

You need about a day & the following ingredients for the finished sarnie:
Crusty loaf (I copied this from the page, but I didn’t like it.)
Steaks
Mushrooms
Shallots
Horseradish & Dijon

I love that they urge you to “serve sliced like cake accompanied by something vaguely vegetable-based to assuage the guilt.”