Thanks for replying - sorry for not responding sooner, I'm not too great at working with the internet yet, so I lost the web site temporarily!

This mushroom had an actual "glaze" - it was kind of sticky, and actually tasted like beef. The soy sauce might work, except that seems more salty than beefy. I'm finding recipes that require "demiglace" - not too familiar with how to do that, I don't think you can buy it. The "Joy of Cooking" gives instructions, which would take about 2 hours to make! So, they say you can substitute beef gravy thinned with water - I may try that.

If you wouldn't mind, pick a few of your favorites and post them for me. I like to do the whole cap (big one) as it makes a beautiful presentation for company. I'm going to try the portobellos in Marsala sauce tonight, and see what happens.