Parsley Sauce

Ingredients

1 ounce butter
1 ounce all-purpose flour (approximately 3 tablespoons plus 2 teaspoons)
Optional: 1 1/2 teaspoons English mustard
250 milliliters/1 cup milk
1 handful fresh parsley (flat-leaf, chopped)
Sea salt (to taste)
Freshly ground pepper (to taste)

Directions

Gather the ingredients.

In a medium-sized saucepan, melt the butter over medium heat.

Stir in the flour and mustard (if using).

Stir thoroughly to form a thick paste.

Cook gently for 2 to 3 minutes more, watching the heat to ensure the paste does not burn. This will cook off the taste of raw flour in the finished sauce.

Gradually whisk in the milk.

Bring to a boil, lower the heat, and simmer for 5 minutes, frequently whisking to make sure there are no lumps. The sauce should be quite thick but still pouring consistency. If too thick, add a little more milk.

Add the fresh parsley and stir well.

Season with a good pinch of sea salt and a few black pepper grinds; taste and add more as needed.

Keep the sauce warm, on low heat, until needed. If keeping sauce warm for more than 15 minutes, laying a piece of buttered parchment paper on the surface will prevent a skin from forming. If a slight skin does form, whisk thoroughly over heat, and it should disappear.