Cover the slices of salt pork with cold water, bring to a boil, drain, and rinse. Brown the steaks (in two or three shifts, transferring them to a plate when finished), drain off the fat from the pan, and deglaze with a bit of red wine or water.
Choose a terrine (earthenware or enameled ironware) of a size, as nearly as possible, corresponding to that of the steaks. Arrange alternate layers of steak and salt pork slices, beginning with a steak and finishing with slices of salt pork, sprinkling the surface of each steak with the seasoned herb mixture. Pour over any juices that may have drained from the steaks, the deglazing liquid, the Cognac, and, finally, the wine and the stock, first a bit of one, then a bit of the other, in order to finish with approximately equal parts of each when the meats, well packed into place, are just submerged.
Prepare a flour-and-water dough containing a bit of oil (which, as the paste cooks, will prevent it from hardening to the point of being nearly unbreakable—one risks breaking fragile earthenware when breaking the seal of the paste, otherwise). Roll it out into a long ribbon on a floured board and fit it into the ridge designed to receive the lid before pressing the lid into place. Put the terrine into a 450° oven and, after about 15 minutes, turn the oven down to about 275° to 300°. Count 3 hours. Break the seal and carefully lift off all the surface fat before serving.