1/4cupflavorless oillike grapeseed or canola, don't use extra virgin or lard unless you plan on warming up the relish before serving, since the fat will solidify under refrigeration
1.5teaspoonskosher saltor more to taste
Inspect the dryad saddles and make sure they're clean. Using a paring knife, gently scrape off the pores (optional, but I recommend it). Holding the mushrooms by the first stem, shave the dryad saddles as thin as possible on a mandoline, discarding any tough stem pieces, then mince as fine as you can stand with a large chef knife.
In a wide pan with high sides, like a cast iron skillet (10-12 inches would be great) gently heat the oil and shallot until translucent.
Add the mushrooms, thyme and bay, and heat on medium until the mushrooms start to give up their juice. Add the water and cook for a few minutes more. Make sure the pan stays wet, you don't want it to dry out.
Once the mushrooms are hot throughout and have wilted/given up their juice, add the vinegar, then season to taste with the salt.
Continue cooking the mushrooms slowly until most of the liquid is gone, you want about 1/4 cup or so remaining to keep them juicy.
Double check the seasoning for salt and pepper, adjust as needed, then cool.
Finally, put the conserve into a labeled, dated container and refrigerate. If you will be keeping the conserve for more than a few weeks, make sure to put a layer of oil on top of the mushrooms so they're not exposed to air.
This is just like duxelles, but with a touch of vinegar instead of the sherry. The vinegar in the recipe makes it more of a preserve too, since the PH is lowered, so it will also last a lot longer than duxelles and doesn't need to be frozen. If you want to keep it in the fridge for more than a week or two, press the mushrooms down in the contianer and cover with a thin layer of oil to stop oxygen (and therefore bacteria) from getting in. I've kept this in the fridge for 6-8 months with no problem, but you could also freeze some if space is an issue.