I’ve seen a lot if charred items going into oil, but not as much going into vinegar. Oil is great if you’re looking for it to spread less on a plate, but I like the way the flavor stands out in vinegar.
I washed a bunch of leeks and threw them on the grill. Then cook them until they’re dark. Cool and grind in a blender with rice vinegar. Let sit overnight then strain through cheesecloth. Use your black vinegar however you’d like. Adding oil in for a vinaigrette nicely mellows the char a bit