Start by chopping up the leeks and mushrooms. They will get strained out, so knife skills are not important. Just chunk them all up.
Heat some olive oil in a large pot (I use the instant pot on sauté).
Sauté the leeks.
Add the mushrooms, and continue to sauté.
Add about 24 cups water (6 quarts), and about 8 Tablespoons of the Better Than Bouillon.
Add the thyme sprigs, peppercorns, salt, and about 2 cups red wine.
Bring to a boil, then let simmer for a few hours while you do the other prep work. In the instant pot, I put it on high pressure for 20 minutes, then let it slow release. I usually leave the broth alone, with the heat on low and just let it sit all day while I prep. (If you’re up for it, and you have the time to really caramelize a bunch of onions, the leftover broth makes the BEST french onion soup base.)