Next, chop your vegetables (essentially make a mirepoix), and add them to a pot, along with your beef, bones, a bay leaf or two, and some peppercorns. Add 2 cups or so of red wine and add enough water to cover everything.
Bring everything to a boil and then simmer it for 2 or more hours.
You could do this part the day before, then cool it and store it in the refrigerator, but if you’re making everything all at once, you’ll want to remove all of the solids, then strain your stock.
Next, reduce your strained stock by about 90 percent. The is a big reduction, but it will really intensify the flavors.
When the reduction is almost reduced to the proper point, add a bit of Cognac and let it cook until reaches the proper thickness.
When it’s done, it’ll be much thicker and richer, and you’ll want to season with salt and pepper at this point.
Start by selecting a potato that’s large enough to yield a good sized wafer, then peel it, and square it off to create a rectangular cube.