Add to the skillet the mushrooms, salt, cumin, chili powder, oregano, and cilantro. While stirring, cook until the mushrooms have reduced, about 5 minutes.
Keeping the heat on medium-low, whisk in the flour and cook for 30 seconds until it’s well incorporated. Whisk in the milk, and while stirring, cook until the sauce has thickened, about 3-5 minutes. Stir in the tomatoes, then stir in the sour cream until creamy and well combined. Taste and adjust seasonings then turn off the heat.
King Ranch bean casserole | www.homesicktexan.com