My fundamental mistake was in how I cut my beef, a folly born out of habit. If you actually want to make Chateaubriand (or something that resembles it) the key is to cut your meat into thin steaks rather than stew cubes.
The other major change I made to the book's recipe, made before my 'oh shit' moment, emerges from the recipe's use of Pickapepper sauce in its seasoning. Not having such sauce, I substituted by mixing an equal amount of A1 and Worcestershire sauce, adding a few globs of local honey to sweeten it up. To this I added the recommended amount of pepper and salt to complete the seasoning.
For meat I used a 2.4ish pound shoulder roast purchased from the local farmer's market.
Another alteration I made to the original recipe was the use of Irish Mist whiskey liqueur rather than rum or cognac, since I lacked both. At this point, though, I had realized that I had screwed up, so it was mostly a futile gesture.
Basically, I turned the dish into a full out stew as a way to salvage. Basically, I mixed in two handfuls of bread flour to thicken it up and served it with the sauce.
This may have been a blessing in disguise. The resulting dish was fantastic. I served it with a couple thick slices of the Italian bread I made yesterday. Happy birthday to me indeed.
What might I do differently in the future? I might straight up turn this into a wine-based variant of stoofvlees, starting with a bacongrease-onion-brown-sugar roux to which I add a little beef stock and a lot of red wine in with the meat and mushrooms. I'm not sure how I'd go on to season my meat. I might opt for a similar improvisational seasoning, or do something with creole seasoning and that local honey.
Anyhow, that's that. Enjoy.
