I'll give you the benefit of the doubt that you're not taking the piss here...

- The water you've soaked dry shiitake mushrooms in
- Stock made from browned veal and beef bones and vegetables, slow simmered for 24 hours and reduced to a sticky paste
- A fermented soy product (Asian section of your market)
- Creme fraiche should work
- Chop mushrooms, saute in butter until brown
- No, do it in a saucepan on the stove top