1/2 pound cultivated white mushrooms, thinly sliced
1/2 cup dry sherry
2 cups chicken stock, preferably homemade
2 tablespoons unsalted butter, softened
2 tablespoons all-purpose flour
2 tablespoons chopped fresh dill
1/2 cup sour cream
Additional kosher salt and freshly ground black pepper to taste
Combine the chuck, half the chopped onion, the garlic, salt, pepper, bread
crumbs, egg yolks and 1/2 cup of water in a large bowl. Mix well and form
meatballs about 1 inch in diameter.
Heat the oil in a large nonstick skillet over medium-high heat. Add meatballs
and cook, shaking and turning, until well browned, about 5 minutes. Don't crowd
the pan; work in batches if necessary. Transfer to paper towels to drain.
Pour off any excess fat from the skillet, leaving 3 tablespoons in the pan, and
add the remaining onion. Cook, stirring often, until softened, about 5 minutes.
Add the mushrooms and cook, stirring, until the liquid they give off has
evaporated, 7 to 10 minutes. Pour in the sherry, increase the heat to high, and
boil until almost all the liquid they give off has evaporated. Pour in the stock
and bring to a boil.
Rub the butter with the flour in a small bowl until it forms a smooth paste.
Pinch off pea-size pieces and add little by little to the boiling sauce,
whisking constantly for 3 minutes. Add the meatballs, stir in the dill and sour
cream, season with salt and pepper, and cook over low heat until the meatballs
are just heated through. Serve hot.
