@cheflayne Sauerbraten for the win.
After 3 days in this marinade:
2 cups water
1 cup cider vinegar
1 cup red wine vinegar
1 medium onion, chopped
1 large carrot, chopped
1 tablespoon plus 1 teaspoon kosher salt
1/2 teaspoon freshly ground black pepper
2 bay leaves
6 whole cloves
12 juniper berries
1 teaspoon mustard seeds
I browned it and braised it in the liquid for about 4 hours at 250, covered. Had to top off the marinade with some home made beef stock and the recipe adds sugar at this point. Not tender after that time. Let it cool overnight in the liquid in the fridge. Sliced it, back in the liquid and low oven for another 3 hours, casserole again covered. Really tender now, not particularly unctuous as we all expected, I mean, it is a round roast. But comparing texture to roasting, it's a draw. I've always thought the texture of the roasted-thin sliced prep was nothing to write home about. I finished the sauce with a bit of port and potato starch to give some body. Only about 2-3 T of port, enough to slightly sweeten and add some complexity without standing out. A lot of recipes use crushed gingersnaps as a liaison but I'm not wild about them.
So, this is WAY more time than a roast but it is almost all hands off and I think the vinegary sauce is unusual and surprising. Takes some planning and it probably won't overtake all the high heat round roast recipes on the internet, but if you scroll through the comment sections for roast recipes, the high temp method doesn't seem as fool proof as implied. I suspect this is more reliable, if not predictable time-wise. I encourage you to give it a try when you can plan a bit.
Thanks for the input. I think I will start hunting for a larding needle.....