Yankee Pot Roast is a beef pot roast cooked along with vegetables in the pot that provides a convenient, one-dish meal. The meat is served on a platter with the vegetables arranged around it.
The vegetables are usually root vegetables such as carrots, onions and potatoes. They are not added right at the beginning with the meat, but rather along the way as appropriate for the cooking time required for the vegetable in question.
As for pot roasts, there’s no actually roasting happening: the meat is being braised. It can be cooked on top the stove with a Dutch oven, or in the oven in a covered roasting pan.
The general assumption is that the pot roast is beef: there’s no reason you couldn’t use pork, lamb or mutton, though purists might look askance at it. Whatever the meat, though, it will be an inexpensive cut of meat suited to this style of cooking.
You could in theory add anything that strikes your fancy, such as garlic, thyme, rosemary, wine or mushrooms. If you do, though, while you may end up with a gorgeous pot roast, it would probably have deviated too far from the New England style of frugal and plain cooking to be called a Yankee Pot Roast.
Quick versions of Yankee Pot Roast have you dump frozen green beans or brussel sprouts in 30 minutes before the cooking is done. Fancier versions roast the whole or large pieces of vegetables to the side, then add them.
The juice and broth can be thickened at the last minute to make a gravy.