In a large, shallow dish, combine the cracked pepper with the bay leaves, fish sauce and 2 tablespoons of the olive oil. Add the steaks to the dish and rub all over with the mixture. Let stand at room temperature for 2 hours or refrigerate for 4 hours.
Meanwhile, in a saucepan, melt the butter. Add the onions and jalapeños and cook over moderate heat until the onions are just softened, 5 minutes. Add the wine and 1 tablespoon of the vinegar and season with salt and ground pepper. Add 2 cups of water and bring to a simmer. Cover and cook over low heat until the onions are very tender, 40 minutes.
Uncover the onions and cook over moderate heat, stirring frequently, until the liquid is evaporated, about 10 minutes. Transfer the onions to a blender. Add the remaining 1 tablespoon of vinegar and puree until very smooth. Season with salt and ground pepper.
In a medium bowl, toss the cocktail onions, olives and mint leaves with the remaining 2 tablespoons of olive oil.
Preheat a grill pan or light a grill. Grill the steaks over moderate heat, turning once or twice, until lightly charred, about 7 minutes for medium-rare meat. Let the steaks rest for 5 minutes, then serve with the onion sauce and pickled onion relish.