Mushrooms taste FUNKY I made this today: https://www.youtube.com/watch?v=Y9gncvPpQKA

The first time I made it, the mushrooms and steak came out great. First cooking the steak, then cooking the mushroom in remaining (steak juices + oil) + butter + thyme on high heat. The mushrooms were a bit shriveled and not plump. They had a nice crunchy texture.

The second time, I decided to cook mushrooms without the steak juices. Also instead of putting the butter and thyme in immediately after the mushrooms, I fried the mushrooms in olive oil on high heat first, then put in the butter and thyme.

This time the mushrooms were disgusting... there was a very strong earthy taste , like the juices inside the mushroom weren't cooked out... Except the problem is, the mushrooms were also starting to get dry, so I couldn't cook them any longer.

What made the difference the 2nd time around that the mushrooms tasted so bad, and how can I avoid dry / earthy-juice mushrooms in the future?
There are three possibilities:


Your mushrooms were bad, if they are a bit off the result isn't likely to be good
Your choice of mushroom was different, with a different flavor
Olive oil burns on high heat, creating off flavors. My money would be on this being your problem. Next time reduce the heat a bit if you want to use olive oil, or use a higher temperature oil like canola (rapeseed). You could also try a bit of water or stock, steak juices are mostly water, not fat, and that would reproduce the conditions of the pan more closely