OmNomNom!

Preheat oven to 300F.

This works for a lb of meat up to as large of a tightly sealed baking dish you have, just adjust quantities. I don't measure anything and just eyeball quantities depending on what I have and what I want.

Beef chuck or any tough cut, cut in 1-2" cubes
1-2" chunks of raw pumpkin
slices or chunks of raw onion
1" pieces of celery
any other hearty veg you like that sounds good -- sweet potatoes, yam, celeriac, etc, are all lovely -- in 1-2" chunks
garlic (anywhere from a whiff to many cloves depending on what you like)
some red wine/raw acv/kombucha or other acidy type liquid
any herbs you like that sound good
salt and pepper
If you want to add a tart note and some antioxidents, add some blueberries, as many as you like. You can stir in some sweetened cranberry or cranberry-orange sauce if you like (I like fresh cranberries mixed in, but they're too tart for everyone else so far *g*)

Mix everything well and put it in a heavy cast iron baking dish with a tightly fitted lid. Put in oven. After 30 minutes turn the oven down to 200-250F and bake until tender, 4-8 hours (depends on how much; smaller amounts and meat in smaller pieces takes less time; larger chunks and larger quantities take significantly longer).

Excellent on day one, even better reheated (in a very low oven) the next day.