If you’re ordering from Amazon, get Healthy Boy Mushroom Soy Sauce too. It’s so good, I use it on every thing, all cuisines. Also way less work than dried mushrooms. I love it with a mushroom cream sauce for pasta, fried rice, anything!
https://www.amazon.com/Healthy-Boy-Brand-Mushroom-Sauce/dp/B007YY6O2I
This sauce was 1:1 ratio of low sodium soy sauce + mushroom soy sauce + some cracked black pepper + a squeeze of sriracha. Sometimes I’ll add a little maple syrup and/or ketchup for sweetness/stickiness. Whatever suits your tastes!
In a lot of Asian grocery stores there is Mushroom Soy Sauce. I use the Thai Healthy Boy brand, here it is on Amazon. https://www.amazon.com/Healthy-Boy-Brand-Mushroom-Sauce/dp/B007YY6O2I
I think one of the keys to easy umami rich vegetarian cooking is understanding the different types of soy sauce. Thailand, for example, has a million, to use differently in cooking or as a condiment.
Are you rehydrating your own TVP? A trick I used to use was to rehydrate it separate from your other ingredients in a heavy broth, so it takes on different characteristics than whatever is in your dumplings.
One last note: a sneaky vegetarian trick (close your eyes vegans!) is to sneak a pad a butter into your sauces and marinades if you want a greater complexity. It's cheating, but complex fat goes a long way. TVP, miso, ginger, scallions...they don't really have any.
I like Thai soy sauce as an all-purpose soy sauce. The Healthy Boy brand is the most popular in Thailand (but not the best) and the one I use. It tastes "brighter" compared to Kikkomon and is paler in color.
Healthy boy oyster (mushroom) sauce+ (Maggi (thai version))[https://www.templeofthai.com/food/sauces/maggi-5150130079.php]
The mushroom sauce is made by the same people that make the most popular oyster sauce, and it’s delicious! For anything that needs a bit more depth of flavor or umami, I add some Maggi too. You can ask restaurants to use Maggi instead of fish sauce when eating out and they’ll usually be able to do it since it’s a staple sauce of Thai cooking.
I am no fan of soy sauce or mushrooms, but... THIS mushroom soy sauce is phenomenal.
My favorite is Healthy Boy Brand Mushroom soy sauce. It's most frequently used in Thai cuisine but is delicious with anything I've tried, so far.