Try this sauce!
Let's see, about 1/4 cup tamari, 3-4 tablespoons vinegar (or lime or lemon), 3-4 tablespoons toasted sesame oil, 2 or so tablespoons grated ginger, same with garlic, about 2 teaspoons honey and enough water to bring level half way up meat. I use this sauce for lotsof recipes. You can shift it around with diffferent sour flavours, or you can add cilantro and fish sauce and reduce the tamari, or you can use molasses instead of honey and add hot sauce.
Just cook the pot roast in this sauce (watered down) for many hours.
Serve it with roasted veggies w/sea salt and a sauteed green.
Yum.
Another idea is to use salad dressing watered down to cook the roast in all day.
Enjoy.