In the bowl of a food processor, combine the olive oil, sherry vinegar, lemon juice, parsley, basil, oregano, garlic and shallots. Pulse until well blended but do not puree. Add 1/4 teaspoon of the black pepper, 1/2 teaspoon of salt, and the crushed red pepper. Remove 1 cup of the chimichurri sauce from the processor and transfer to a non-reactive bowl, cover with plastic wrap and reserve at room temperature for up to 6 hours. (If cooking steak another day, refrigerate sauce and return to room temperature before serving.)
Season the steak with 1 teaspoon of the kosher salt on each side, as well as 1/4 teaspoon of the black pepper per side and place in a large, resealable plastic bag. Add the remaining chimichurri sauce from the processor. Seal bag and refrigerate the steak for at least 2 and up to 4 hours.
Preheat a grill to medium heat.
Once the steak has finished marinating, remove it from the refrigerator and let it come to room temperature for 30 minutes. Brush the excess chimichurri sauce off the steak and set the steak over the hot grill. Cook for 6 minutes on the first side. Rotate the steak 45 degrees, and cook another 6 minutes. Turn the steak over and continue to cook until the steak is done, about 6 to 8 minutes for medium-rare. Once cooked, lay the steak on a clean cutting board, and allow it to rest for 5 to 7 minutes before slicing across the grain into 2-inch wide strips. Serve with crusty bread and the reserved chimichurri sauce.