Place the steaks in a single layer in a large glass or ceramic baking dish. Whisk the remaining ingredients together in a bowl and pour over the steaks, making sure both sides are coated. Cover loosely and refrigerate for 12, or preferably 24 hours, turning every 2 or 3 hours.
1 1 /2 hours before serving, make the sauce: combine the tomatoes, vinegar, cilantro, olive oil, salt, and pepper in a blender. Blend for 1 minute, or until smooth and emulsified. Transfer to a glass or ceramic bowl, add the onion and green pepper, cover with plastic wrap, and let sit at room temperature.
Half an hour before serving, remove the steaks from the refrigerator and allow them to come to room temperature.
When ready to serve, preheat a grill or griddle pan to high heat. Shake the steaks dry and grill them for 6 to 8 minutes on each side, or until done to your liking. Let the steaks rest, loosely covered with foil, for 5 to 7 minutes. Carve the meat across the grain into 1 inch slices and serve with white rice and Molho Campanha.
c.1997, M.S. Milliken & S. Feniger, all rights reserved