One of the hardest things about making a pan sauce at home is getting a perfect rich and silky texture instead of a thin, watery one. Kenji just shared some great insights into this, including the importance of deglazing the pan with stock that's loaded with gelatin. I'd like to add one more method to the pan-sauce technique arsenal: heavy cream.
I was thinking about this recently while examining the use of olive oil for high-heat cooking. In one of my tests, I seared skirt steaks in both olive oil and canola oil, then made a mushroom-cream pan sauce for each one. At the time, I was curious to see if there was a significant flavor difference between the two batches (there isn't). But there's a lot of be said about the cream in that pan sauce, too. Plus it's tasty, so I figured I'd share the recipe with you.*
In the final recipe, I'm calling for vegetable or canola oil for searing, but go ahead and use olive oil if you want; the dish should taste more or less the same.
See, the cream in this pan sauce plays a very similar role to both the gelatin-rich stock and the butter in Kenji's recipe. As Kenji explained, gelatin is a protein that acts as an emulsifier, forming a matrix that impedes the flow of the sauce's fluids (i.e., water and fat), creating a thicker viscosity and preventing the fat from coalescing and separating out of the sauce. Butter, meanwhile, adds fat that rounds out any sharp flavors in the sauce while helping to thicken it even more as it becomes part of the emulsion.
In the case of heavy cream, it's supplying both qualities at once. First, it's full of butterfat—starting out around 38% and going up as the cream reduces in the pan. Second, it comes pre-loaded with its own set of emulsifiers, proteins that help keep the butterfat dispersed throughout the water content of cream without coalescing. Add cream to a pan sauce, and those emulsifiers go to work helping you create a great emulsion right there in the skillet. Plus, those emulsifying proteins work even better as they're heated, meaning that you can safely bring a cream sauce to a hard boil without fear of it breaking.
In this recipe, I start by searing skirt steaks until browned outside and medium-rare within. I recommend doing this in two skillets, to avoid crowding the pan so that the steaks brown really well. Once they're done, I set them aside and proceed with the pan sauce.
Then I divide sliced cremini mushrooms between the two skillets and cook them until they've dumped their fluid and most of it has cooked off (once again, two skillets speeds all of this up). I add minced shallots, garlic, and thyme, and cook it all together until the mushrooms are browned and the shallots are soft and golden. This can take several minutes, so be patient.
I deglaze both pans with white wine, scraping up the fond (browned bits). At this point, you can consolidate everything into a single pan by scraping the contents of one into the other. I let the wine fully reduce, then add some chicken stock and let that reduce as well. The cream is going to give us lots of thickening and emulsifying power, but if you have gelatin-rich chicken stock, it won't hurt to use it here...there's not really such a thing as too much emulsifying power. If you don't, that's fine too—the cream is going to do the job.
With the chicken stock reduced by about half, I add some cream and boil it all until the sauce has reduced slightly and thickened to a nice, rich consistency.
Then I add the steaks back to the pan, bathing them with the sauce to re-warm them.
It may be that all of your dining companions will be thinking, Yum, mushrooms and cream!, when they dig into their plates. But not you, no. You'll be thinking, Thank you emulsifiers and butterfat.