Mushrooms Poached in Sour Cream

This is a mild, rich side dish, one that can double as a sauce for buttered noodles or rice (it can be served on toast too). With chanterelles or other wild mushrooms, it's a dream, but even with button mushrooms it's super. If you have spring onions, this is the place to use them; otherwise, leeks are a great substitute.
- 4 tablespoons (½ stick) butter
- ½ pound spring onions or leeks, trimmed, cleaned , and chopped
- 1 pound mushrooms, trimmed and sliced
- Salt and black pepper to taste
- 1 tablespoon flour
- 1 cup sour cream
- Juice of ½ lemon
- ¼ cup chopped fresh dill or parsley leaves
Instructions:
- Put the butter in a skillet over medium-high heat. When the butter foam subsides, add the onions and cook for a minute. Reduce the heat to medium and add the mushrooms, along with some salt and pepper. Cook, stirring occasionally, for about 10 minutes, or until the mushrooms have given up most of their liquid and begun to brown.
-  Stir in the flour and cook for a moment, then add the sour cream and reduce the heat to low. Simmer for 3 to 5 minutes, then stir in the lemon juice.
- Taste and adjust the seasoning, stir in the dill, and serve immediately.