With a combination of porcini powder (ground dried porcini mushrooms), nutritional yeast, MSG, miso, kombu, and something with hydrolyzed vegetable protein, you can make some almost-meaty tasting stocks that have as much richness/flavor/oomph as any bone broth. I'm not vegetarian, but I have friends and business partners who are, and I like a challenge. Any four of those six (careful with the yeast -- it gets overpowering quickly) can combine for a pretty powerful stock or sauce. I use most of them in my regular cooking, too.