For Dry Brine:
3 1/2 to 4 teaspoons kosher salt (use 1 teaspoon per pound of beef)
1 teaspoon ground black pepper
1 teaspoon granulated garlic
3 1/2 to 4 pounds top round beef roast (sometimes sold as "London Broil")
For Roast and Pan Gravy:
1 tablespoon vegetable oil
1 yellow onion, diced
3 cups torn miatake (hen-of-the-woods) mushrooms, or any mushrooms
1/2 teaspoon kosher salt
2 tablespoons melted butter
1 tablespoon cold butter
1 tablespoon all-purpose flour
2 tablespoons sherry vinegar or any wine vinegar
2 cups high quality, low-sodium beef broth
salt and freshly ground black pepper to taste
1 pinch cayenne pepper, or to taste
1 teaspoon freshly picked thyme leaves
Combine 1 teaspoon salt per pound of beef, 1 teaspoon black pepper, and granulated garlic in a small bowl and mix well. Set the beef on a piece of butcher paper, and apply half of salt mixture evenly to each side, tamping it on lightly with a fork. Press the sides of the roast onto any seasoning that has fallen onto the paper. Place beef on a wire rack set over a pan. Refrigerate the “dry brined” beef, uncovered, for 24 hours, turning meat over once after 12 hours.
Preheat the oven to 475 degrees F (245 degrees C).
Heat oil in an oven-safe pan or skillet over high heat; add beef to pan and sear on both sides until nicely browned, about 3 minutes per side. Using tongs, pick up the meat and sear on the sides as well, if desired.
Turn off heat and add onions to the pan wherever they fit; top with mushrooms. Season vegetables with the 1/2 teaspoon salt. Drizzle melted butter over vegetables, and brush melted butter over beef.
Roast in the preheated oven for 15 minutes.
Reduce oven temperature to 325 degrees F (170 degrees C), and continue to roast beef until desired internal temperature is reached. Begin to check temperature after 15 to 20 minutes. For medium-rare, an instant-read thermometer inserted near the center of beef should reach 125 degrees F (52 degrees C). For medium, internal temperature should reach 130 to 135 degrees F (54 to 57 degrees C). Total roasting time will depend on the size of the roast.
Remove beef from the oven, transfer to a plate, and cover loosely with foil. Let rest at least 15 to 20 minutes before slicing.
Meanwhile, prepare the gravy. Remove mushrooms from the pan, and keep warm until ready to serve.
Melt 1 tablespoon cold butter in the pan over medium-high heat; sprinkle in flour, and cook, stirring, for 2 minutes. Whisk in vinegar and beef broth, and bring mixture to a boil, stirring occasionally. Season with salt, black pepper, and cayenne to taste, and add thyme leaves.
Continue boiling on medium-high heat until gravy reduces by about half and thickens slightly. Gravy can be reduced more for a thicker texture.
Once meat is rested, slice thinly at a 45-degree angle, and serve with mushrooms and hot gravy over the top.