Combine the wine and port with the onions, mushrooms, garlic, chile, parsley, and thyme in a 3- or 4-qt. saucepan. Bring to a boil and then simmer very briskly until the liquid is reduced by half, about 10 minutes. Add the broth and reduce by half again, about 13 minutes. Strain the liquid and discard the solids. Clean the saucepan and return the strained liquid to the pan. Reduce until there is just over 1/3 cup liquid remaining, about 5 minutes.
Grill or broil the steaks: Prepare a medium-high gas or charcoal fire or heat the broiler on high. Season the steaks with salt and pepper and grill or broil until they are cooked to your liking. Medium rare takes about 1-1/2 minutes per side; medium, 2 minutes per side. Let rest while you finish the sauce.
Bring the wine reduction to a simmer. Remove from the heat and whisk in the butter. Season to taste with salt. Spoon a tablespoon or so of sauce over each steak.
Make Ahead Tips
The sauce can be made up to 2 days ahead (but don't add the butter until you're ready to serve). Refrigerate if working more than a few hours ahead.
nutrition information (per serving):
based on four servings;
sat fat g
Photo: Scott Phillips