This rich, savory gravy can be made a couple of days in advance and kept in the fridge. Reheat on the stovetop or in the microwave, adding a little extra broth to thin. After thinning, you might want to adjust flavors by adding a dash more salt, pepper, soy sauce, lemon juice, and/or mushroom base.
3cupsliquidwater, broth, or reserved porcini liquid from yesterday's [Mushroom Meatloaf post]
1tablespoonlemon juice
2teaspoonssoy sauce
Instructions
Melt 2 tablespoons of the butter in a large skillet over medium-high heat.
When butter is bubbly but not burning, add onions and cook, stirring occasionally, until onions are nicely browned and even a tiny bit burnt (8 to 12 minutes).
Add garlic, mushrooms, salt, and pepper. Cook, stirring occasionally, until the juices from the mushrooms have been released and mostly cooked off.
When the pan begins to get dry, deglaze with sherry or wine, continuing to cook for about minute more to let the sherry or wine reduce.
Remove from heat.
Transfer the mushroom mixture to a bowl and set aside. Give the pan a quick wipe with a paper towel and return to a medium-low heat. Melt the remaining 4 tablespoons of butter in the pan. Whisk in flour and continue to cook, stirring vigorously, until roux resembles a thick paste and is a light golden color (3 to 5 minutes). Add broth or other liquid, whisking thoroughly to smooth out the flour lumps. Increase heat to medium-high, add mushroom mixture back to the pan, and bring to a boil. Reduce heat and simmer, uncovered, until somewhat reduced (7 to 10 minutes). Stir in lemon juice and soy sauce. Taste and adjust seasonings if necessary.