English Mushroom Sauce

A short compound sauce that depends entirely on the brown sauce underneath it, which the book assumes you have already made. Read that recipe first, because everything here is a garnish for it.

• Strained stewed tomatoThis is stewed tomato pushed through a sieve to remove seeds and skin, roughly what passata or a thin tomato puree gives you. A third of a cup of canned tomato puree, loosened with a spoonful of water, behaves the same way.
• The double boilerOnion and butter over water will only sweat, never brown, which is the point here since the browning comes from the sauce. It takes the full fifteen to twenty minutes to go soft and sweet; rushing it in a dry pan gives a raw onion bite that the short reheat will not fix.
• Mushrooms need more than a reheatChopped raw mushrooms stirred in at the end release water and taste flat. Cook them separately in a little butter until they have given up their liquid and it has evaporated, then add them, or let the finished sauce simmer gently ten minutes before serving.
• Half a cup of mushroomsThe recipe measures them before chopping, so roughly 2 oz of button or cremini caps. Cremini or a few dried porcini soaked and chopped will carry further in a sauce this plain.
• "Other seasonings"The recipe lists only salt, so the phrase means whatever you keep for brown sauce: black pepper, a bay leaf, a little lemon juice or a dash of mushroom ketchup or soy for depth.
• SaltA teaspoon into roughly two and a half cups of sauce is a lot if the brown sauce is already seasoned. Add half, taste after the mushrooms have gone in, and correct at the end.
• YieldAbout two to two and a half cups, enough for four to six servings over croquettes, baked potatoes or toast.