Place dehydrated porcini mushrooms into your food processor and grind until they are nothing but dust. Word to the wise... allow to sit for a few minutes before opening or else you might get a mushroom dust bomb in your kitchen.
In a small bowl combine ground porcini mushrooms with sea salt, pepper, crushed red pepper and sugar, mix to make the rub.
Remove steaks from the fridge. Rub into steaks evenly and on both sides. Allow to rest and marinate for 20 minutes so it forms a paste and sticks well.
When ready to cook, heat seasoned cast iron to just before smoking point. Depending on the size you might need to cook steaks two at a time to avoid overcrowding the pan. Heat over HIGH heat and turn on the fans to prevent the smoke detector from going off.
Sear on each side for 3 (medium rare) to 8 (well done) minutes depending on desired temperature and thickness of meat. These were 1 1/2 inches and rare- I cooked them for 3 1/2 minutes per side. When cooking do not move the steak around, keep it in the same place except to flip. In contrast to cooking other pieces of meat in cast iron, do not baste with the butter. Basting will wear away at that beautiful crust you worked so hard on. If you have someone that requests "no pink", you might be better off baking at 400 for 4-5 minutes instead of searing for the full 8 minutes. You don't want the outside to burn.
About 1 minute before you remove the steaks, add 1 tablespoon of butter directly to the top to melted over meat. If you add it too early, it can burn, so wait until right before are ready to remove it.
Remove steaks from the skillet and allow to rest for at least 5 minutes. Meat holds heat well so do not worry about them getting cold. Resting helps the juices (and flavor) to reabsorb back into the meat instead of ending up on your cutting board.
When plating, drizzle with balsamic reduction sauce and serve.
If you've tried this recipe, come back and let us know how it was in the comments and ratings.