Well... how exotic do you want to get with this sauce?
You could use the gel filtration-freezer method to produce a black pepper consomme, then use the consomme as a base for your sauce.
My first inclination would be some kind of cream-based sauce. I'd take a bunch of whole black and white peppercorns and toast them in a pan over medium-high, let them cool, and very coarsely grind them with a rolling pin or something similar. Maybe the back of a pan. Then I'd add them back into a pan with some butter, shallot, fresh rosemary and cook for a minute or two. Then I'd deglaze with white wine or vermouth and beef broth and reduce to syrup consistency. Then I'd add heavy cream and a tiny dash of fresh ground nutmeg, bring to a boil, then reduce the heat and cook at a simmer until the cream is reduced and coats a spoon. After that I'd pour in all the jus that's collected from the steaks, and let it cook a few seconds longer. Then I'd strain out all the solids, whisk in a tablespoon or two of cold butter off the heat, check seasoning, and then put on top of steak. Better if you cook the sauce a la minute. That's what I would personally do, not having a "pepper sauce" recipe handy.