I made this last night and I'm writing it down so I don't forget it.
Take one lb. of good ground chuck (80/20) and put it in a bowl. Add 1 tsp garlic powder, 1 tsp. onion powder, and plenty of freshly ground black pepper. Mix well, then form it into patties of a roughly oval shape. I made two, but I'd probably make 3 next time.
Cook the patties in a skillet until almost cooked through, then remove to a plate. Add 8 oz. sliced cremini mushroom along with a tbs. or two of butter. When the mushrooms are cooked down and starting to brown, add one cup of broth (I thought I had beef, but I didn't so I used chicken), three or four sprigs of chopped fresh tarragon, a couple of dashes of Worcetstershire sauce, a couple of dashes of sherry vinegar, and a bit of salt.
Mix 2 tsp cornstarch with water in a separate glass, then stir in. Return the patties to the skillet and simmer until the gravy is thick and the patties are cooked through. Put the patties on a plate and spoon over the gravy.