Making gravy per usual is a by-product of roasting or pan-frying something. At that point, you take whatever jus you have in the dish and that essentially determines how much real gravy you end up with after you've de-glazed, added stock/water, flour, etc.
Looking for a method that results in more gravy (jus?) without wasting more meat/food. I'm assuming certain cooking temperature/method/meat results in more jus and gravy. That's what we're after here.
If you want more gravy you need to add more liquids and natural flavours.
Better if you have bone but . . . no bone:
Before you roast your beef sear it, so it has good colour when it comes out, deglaze the pan/baking tray with water/red wine/white wine or Madeira one of me faves and put that to one side. (in the gravy stock pot)
Add onions, carrots and parsnips in with the beef, and touch of water, olive oil and salt. Don't go mad with the water you're not poaching the beef!! Just enough to stop the veg burning - 5mm in the bottom (top up if needed).
When the beef is ready (55C internal temp = medium rare more here) take it out of the tray, put the root veg to one side and and add the remains to your gravy stock pot.
Sear the bottom of the roast with a little oil (it'll be a bit soggy from sitting in the veg) then put it aside to rest (5-10 mins if you're in a hurry 15-30 for 3kg will come out lush!) deglaze again adding the resulting jus to your stock pot, which now had a wealth of flavour.
Use that stock pot to create a beast of a gravy! Make it in the usual manner, if you keep the onions in they'll make it thicker and tastier - a stick blender with give you a smoother texture if that's what you like!
I learnt that if I only add one-half inch of water during the roasting time I have loads enough gravy, and it is delicious too. I have always worried about the concern about steaming, but this method works great, provided you do not add more than the half inch at a time! Keep an eye on your roast and add water or broth when needed. I usually use both in the pan.
When I want to either increase the amount of actual gravy I already have or increase the liquid that I will thicken I add what I think is one of the greatest fairly new products, and that would be Better than Bullion (BTB). It comes in any flavor you could possibly want, with a whole range of varieties, I suggest you go on their website. It will also give you recipes, tips, and even a conversion calculator. They have a product for anything you want to do with flavor, meat or veggie, even low sodium. For gravy use the calculator to determine how much liquid and BTB you need. Beyond this flavor enhancer you can add a cream soup, flavor appropriate or even a bit of sour cream. I hope you are as happy with BTB as I am, Happy Cooking!
Anything that would increase the pan drippings would require the moisture to come from somewhere ... such as heating the meat too far, so that it becomes tough and dry (squeezing the moisture from the roast).
It won't help when cooking the roast this time, but if it's bone-in, you could take the bones to make stock for use in your next roast.
You could also add other ingredients to provide moisture; I generally roast meats on top of a bed of carrots and onions, and the onions release quite a bit of liquid.
