I don't advocate reusing marinades beyond well, marinading, however if you're going to cook it at a rolling boil for hours, that is perfectly safe. So, really, the marinade preforms triple duty here: to season/tenderize the meat, the meat cooks in it, and then it becomes to gravy!
1 chuck roast (mine was about 3 pounds, bone in)
Measure out your vinegars, and water (or broth!), and add those to the baking dish. You can easily heat all of this up in a sauce pan, until the salt and sugar dissolve, but I didn't bother with that, since it was all going to be sitting together for a few days.
In goes the apple cider vinegar and water!
Once it is all mixed well in the baking dish, add in your roast, cover with plastic, and pop it into the fridge, to sit for at least 3 days, up to 5. Obviously, the longer you let it sit, the more sour the meat becomes, so if you don't want a strong flavor, you may want to let it marinade for only 2 days.
Flip the meat every day, to ensure that both sides are getting equal time in the marinade. This is the flip on the second day:
This is what the meat will look like by the third day; you may not notice a huge difference (aside from a color change), but believe me, a huge change has taken place! Take your meat out, lay it on some paper towels, and pat it dry.
Dredge your roast in the flour (depending on the size of your plate, you may have to do it in sections...my plate was a lot smaller than my roast, so I could only dredge this 1/2 of a side per time...), while you're doing this, have a pan that will fit your roast preheating over medium high heat on your stove.
If you can fit this in a dutch oven, even better to brown your meat in the same pan you're going to cook it in. My roast wouldn't fit in the pan I ended up cooking it in, so I had to sear it off in a large skillet, and transfer it to the dutch oven. You'll see what I'm talking about in a minute.
Like I mentioned earlier, don't toss out that marinade! Let your roast sear on each side until it is deep brown. I would have liked for mine to get more brown, but I lost tract of time the afternoon I made this, and was rushing so we wouldn't be eating at like, 9 o'clock that night!
When your roast has sufficiently browned, pour the marinade into your dutch oven (or, you could easily do this in a crock pot. At this point, you would just pour the marinade into the crock of your slow cooker/crock pot, add in the roast, and let it cook for 7 hours or low, or for 4 hours on high). Add your meat, and cook on a low boil for 4 hours, or until your roast is tender. At this point, you can slice your roast, but I like to just shred mine up into large chunks.
After your roast has cooked, pull it out and let it rest while you work on the gravy (if you choose to make the gravy, and I recommend that you do. It's yummy!)
Put the gingersnap cookies into a food processor, and pulse until they are fine crumbs.
This roast literally falls apart; you can see it pulling away from the bone. This is some seriously good stuff.
Now that your cookies have been pulsed into crumbs, strain the solids out of your cooking liquid/marinade. I also put the liquid into a fat separator, since the roast let off a good amount of fat while cooking, and I didn't want all of that in my gravy.
Return the liquid to your pan, and add in the gingersnap crumbs. This will thicken up pretty quickly, cooking over medium heat, whisking steadily.
Once the gravy has reached the consistency that you like (if it thickens too much on you, you can thin it out with some beef stock, or even just water if you don't have anything else). The meat is tangy, and moist, and this will become a steady meal in your house! I do hope you try it!