Preheat the oven to 275 degrees. In a bowl, mix the pepper, salt, brown sugar, soy sauce, vinegar, and 1 teaspoon of the olive oil. Rub 2 teaspoons of the paste all over each steak. Wrap the steaks individually in plastic and let stand at room temperature for 1 hour.

Meanwhile, on a double-layer square of aluminum foil, toss the garlic with the herbs; drizzle the remaining 1 tablespoon of oil on top. Fold the foil to enclose the garlic and transfer to a baking sheet. Roast for 45 minutes, until the garlic is very soft.

When the garlic is cool, squeeze the cloves from their skins into a bowl; add the herbs. Using a fork, mash the garlic with the herbs and butter. Spoon the garlic butter onto a sheet of plastic wrap, roll into a log and refrigerate until firm, 30 minutes.

Build a very hot fire on one side of a charcoal grill or light a gas grill. Unwrap each steak and grill over high heat for about 7 minutes, turning once, for rare meat. For medium-rare, transfer the steaks to the cool side of the grill, close the lid and cook for 4 minutes longer, turning them once halfway through. Top the steaks with the garlic-herb butter and let stand for 5 minutes, then serve.