I tried a couple of months ago...failure.

4 people standing rib roast, 2 bone cut seasoned and tied from the local butcher shop. 4.5 lbs. cooked low and slow.

Au jus: 4:lbs bones: one knuckle, 3 marrow, 1 lb “stew meat”. Roasted at 350 for 1-2 hrs in a sheet pan, drained off fat, deglazed pan with water. Simmered for 2-3 hrs with carrot, onion, thyme, parsley, rosemary. Drained, refrigerated.

Result: Flat brown water, added better than bouillon.

Maybe Au Jus is used to moisten the meat, but creamy horseradish also adds moisture. I prefer brown gravy over Au jus served over mashed potatoes.

My attempt did not equal Knorrs Au Jus Mix.

I have ordered Demi Glas Base for my next attempt.

This is the recipe I used the last time we had a wonderful Prime Rib. The Au Jus was praised and there was none left - in fact I wished I had made more. The Italicized wording are my addition to the recipe.

Chef John’s Beef Au Jus

https://www.allrecipes.com/recipe/221957/beef-au-jus/print/

This is the most minimalist method for doing a quick au jus for your prime rib of beef. Chef John

This au just came together so well and was so easy and very tasty. WC

1/4 cup beef fat drippings from a prime rib or other roast beef (see footnote) I never could find a footnote.

1 1/2 tablespoons all-purpose flour

2 cups beef broth maybe a bit of white or red wine and some minced garlic from a jar

salt and ground black pepper to taste

You will use the drippings from the pan your prime rib was cooked in. Drain off most of the fat, but leave about 1/4 cup in the pan. Save the drained for Yorkshire Pudding.

Place pan used to cook roast over medium-high heat that contains the 1/4 c fat and drippings and melt fat. Whisk flour into beef fat; cook, whisking constantly and mixing all of the fond into the fat and flour and be sure to get every speck of it, until the mixture thickens, about 3 minutes.

Pour in video he said to drizzle in cold beef broth (he said not to use bouillion) into fat mixture; increase heat to high and bring mixture to a boil. If you serve it now, it will be thin like a traditional au jus. If you boil it for 5 minutes it will be thicker, which he said is the way he prefers it.

Boil mixture until it thickens slightly; season with salt and pepper to taste.

Serve in ramekins on each individual plate while it is boiling hot. Makes about 1 1/2 cups

Try Johnny's French Dip Au Jus concentrate. Yeah, a salt bomb but pretty good.

https://johnnysfinefoods.com/products/concentrates/french-dip-concentrate-8oz/

johnnys was too salty for me.

Interesting, @User. To me brown gravy is altogether different; it must depend on where one lives in our great nation. I looked all over the internet for au jus recipes and they all use the pan drippings, beef broth, and a bit of flour, just as the really simple one from Chef John.

Also, flour or some alternate starch source is an ingredient in all packaged au jus mixes.

I confess, I always wing it and taste and taste as I go:

Beef broth, beef drippings (deglaze roasting pan), butter, garlic, onion, Worcestershire sauce, dry sherry, corstarch and water, salt and pepper. Some times I add soy sauce. Saute the garlic and onions in butter until soft. Add some beef broth and whirl it with a stick blender till smooth. Add reamining ingredients except cornstarch and water and heat until boling. Add a little cornstarch mixed with water to give it a bit of body but not to thicken it. Cook until it has just a slight bit of body.

It is best with homemade beef broth but I have used Kitchen Basics Beef Broth as well.

I don't know how the term is used outside of my orbit, but here “au jus”, meaning “with the juice”, is literally the pan juice. The seasoning is whatever fell off the roast. Perhaps with a little extra of the same if not enough got into the juice. Heat lightly and use a wooden spoon to scrape up the fond. Add water if it's too reduced.

The oxtails should be good if they're meaty. If you're making them for dinner, prepare as you will. If you're sacrificing them to the cause, I'd go halfway between braise and roast—liquid in the bottom (about halfway up) to extract more meatiness and well exposed to the air to add more flavor with caramelization. Mirepoix will add flavor, but make it more like stock. The liquid can contain some red wine, which is earthy, mushroom stock, which brings the umami, demi-glace (taste for salt level if it's bought), which will add depth of flavor, tomato juice, or just plain (good tasting) water. Once caramelized, flip to get the flavor into the liquid. Cook the dickens out of them. After it's mostly cooled, squeeze the meat to get the last of the liquid and what's been absorbed. If the meat isn't beyond edibility, either cook longer or put it in soup. If it's just shreds of fiber, throw it out. When you reheat, taste for seasoning and adjust. Remember, salt magnifies as liquids reduce.

An alternative might be to reduce a lot of good beef broth with a bit of beef or mushroom (and bouquet garni, optionally).

But I agree that flour goes in gravy, not real jus.

After reading the comments of @User and @plllog, I was very intrigued. My mother never made an au jus so I had no idea of how it was made, and I have been cooking for many, many years. I went on another search of the internet. Everything I found had a small amount of thickening agent in it; so I gave up. Then I had to look for some kind of pork to add to my curbside grocery order. Decided to look at the recipes of the grocery store's site. Now this is a state-based only grocery store, and I was shocked to see their two recipes for au jus.

Dijon Au Jus

2 cups beef broth

1 cup cabernet sauvignon

3 sprigs of fresh thyme

4 garlic cloves, smashed

2 T Dijon mustard

Combine broth, wine, thyme sprigs, Dijon mustard and garlic cloves in a pot. Bring to a simmer and reduce by half, strain liquid of thyme sprigs and garlic cloves. To serve drizzle Dijon au jus over roast beef as desired.

Easy Green Peppercorn Au Jus

1 Tsp olive oil

1 Tbsp shallots, minced

1 Tbsp soy sauce

1/2 Tbsp Worcestershire sauce

1 Tsp Dijon mustard

8 oz peppercorn sauce

1 cup beef bone broth

1 Tbsp parsley, minced

Heat a medium saucepan over medium heat. Add oil and shallots and cook 2 minutes or until shallots are translucent.

Add soy sauce, Worcestershire sauce, Dijon mustard, and green peppercorn sauce. Whisk to combine.

Whisk in beef bone broth and bring to a simmer. Remove from heat and stir in parsley. Keep warm for serving. Serves 6

So, @cookebook, these recipes give us both a starting point to adapt develop what we would like to see in a true au jus. And, I want to thank both @User and @plllog for educating me about au jus. And I love that I found these more traditional recipes for au jus on a grocery store web site. Plus I love any day when I learn something new, it really makes my day.

I also wing it...in the pan the beef was cooked in, drain almost all the grease and add water and red wine to deglaze....then I add some "better than boullion" paste, worchestershire, a bit of soy sauce....careful not too much it's salty. Simmer to get rid of the boozey flavor of the wine....maybe add more better than boullion...
Never EVER any flour or starch. It should be clear. When you add thickening you are making pan gravy.

Leave the meat to rest in the roasting tin, covered, to allow the jus to come out if the meat. 15 mins or so. Move the meat to another dish, drain off some fat. Add liquid.......wine, water.......and boil and scrape, add good beef demie glace if you need more than is in the pan and whisk in a knob of butter. You won't have a lot.

To clarify, I recognized that Au Jus should be juice. I use just a tad bit of cornstarch just to give it gloss and mimic a mouth feel similar but certainly not identical to a good gelatinous stock.

Thanks all!