When I make gravy, I usually just go by gut feel.  I'll saute some shallots and possibly mushrooms in butter, add beef stock/broth, red wine, a couple of bay leaves, a few sprigs of time.  Cook until reduced down.  Remove herbs.  Hit it with an immersion blender, season with salt and pepper, then add a thickener.

In terms of thickeners, corn starch is the best in my opinion.  A little goes a long way, so it won't have a huge carb impact (even though it's not keto).  You could also add some xanthan gum as a thickener.

Sorry it's not a recipe.  I find that most anything I do in a saucepan is done by instinct for me (and lots of tasting along the way)

@ketoadmin thanks for that Steve.  That is pretty much where I was headed.

I’ve been contemplating the lack of gravy on my plate throughout the holidays. I tried something this week that I think will work in an amazing way moving forward. I was totally impressed with the results. Sodium alginate, a brown algae product worked fabulous when I cooked a pot roast this weekend. Sometimes I dread making a turkey or a pot roast because I love the gravy and of course, flour or cornstarch based gravy is a no-no for keto observers.

I ordered some sodium alginate from Amazon and did a little research. Starting with my beef broth from the pot roast, I added 10 radishes in the last half hour of baking. With my immersion blender, I puréed the radishes in the broth for some added substance that a flour-based roux would give it. Following that I sprinkled in about a teaspoon of sodium alginate. It thickened quickly (about 30 seconds) as I incorporated the powder into the hot broth with my immersion blender.  It did not affect the taste at all of my broth with the herbs. The radishes provided no flavor but some texture to the gravy. It had a silky mouth feel like my regular gravy. It was not gummy or slimy at all!

Xanthum gum tends to add a slimyness to the final product. Yuck! The use of the sodium alginate was fabulous! The texture was spot on.  

There was only a moderate glucose spike typical with eating a meal. No extraordinary glucose spike as a result. I thoroughly enjoyed my pot roast and beef gravy with a smile on my face knowing that I can remain in ketosis and enjoy one of my favorite Comfort food things. I’m going to try it next on the baked chicken on Wednesday. I realize this is lengthy but my enthusiasm is growing. 

Sodium alginate thickens in the presence of calcium and does not work when there is dairy in the mix. I found a research document on how to use it and will post it a little later this afternoon for everyone’s information. I’m feeling encouraged about this. 😀

I've used it before doing spherification back in my modernist cuisine days.  I never thought to use it as a thickener...