It can be done with crudes trotters, but it will give you a little more work at the time of cooking. I chose to buy them in a Super.
Make a sauce with onion, garlic, and tomato. When ready, add the trotters and cognac. Once evaporated, pour the beef broth, until the cover.
When the juice boil again, add the mushrooms (which we will have had to soak for 1 hour).
After 20 minutes we make "la picada", with the ingredients indicated in the recipe, and pour into the pan. Five minutes and stop the fire. Let rest a bit and serve.
To make the "Picada"
We will put in a mortar the ingredients listed in the recipe and crushed all, adding a little juice from the pan, until a fairly thick sauce.