Tenderize steaks then season both sides with a little salt and pepper.
Mix flour, salt and pepper together (or just use seasoned breading) and place in a pie pan.
Dredge the steaks in the seasoned flour, shake off the excess, set aside.
Position rack to lower middle slot of oven and preheat to 300 degrees F.
Add enough oil to just cover the bottom of a Dutch oven set over
When oil shimmers add steaks to the pan. Don’t overcrowd. Cook until
golden brown on both sides, ≈ 2 minutes per side.
Remove steaks and repeat until all of the steaks have been browned.
Add onion and garlic to pot and cook/stir for about a minute, then add the mushrooms
and cook/stir about 2 more minutes. You want the onion to caramelize and the
mushrooms to start giving off their liquid.
Deglaze the pan using a wooden spatula and the red wine.
Add stock, Worcestershire, mustard and thyme and mix.
Add steaks, nestling into the sauce so they are all submerged.
Cover dutch oven and move to oven for 2 hours.
Remove steaks from sauce (careful, they will be fall-apart tender), cover in foil to keep warm and set aside.
Now, the gravy:
Mix cornstarch with a little warm water to make a thin, pour-able paste.