Actually sort of. I mean I guess what you would call a soup. Though the Chinese would just consider that a sauce. The put that shit on everything. Well different sauces. Here’s a random picture of a Chinese school lunch.
https://whatsforschoollunch.blogspot.com/2009/08/china-school-lunch-fish-and-vegetables.html
You see how the veggies are glistening? They’re covered in a sauce made with cornstarch and broth. Even the fish has a layer of sauce on it.
So yeah, a sandwich would be pretty dry. But that’s not really what they’re talking about.
In Chinese food, there’s an insane amount of seasonings that basically go in everything. At a minimum they use something called 5 spice which is a mixture of you guessed it, 5 spices. So the dry they’re referring to is actually seasoning. So something like a subway sandwich with italian dressing, salt, pepper and oregano wouldn’t be dry in the way they’re using it. They’re really just referring to the sandwich being unseasoned. Also, here’s a tip, if you’re going to make a sandwich, season it. Even just adding salt and pepper will make it taste way better.
Yup, that’s what the Chinese are saying when they say it’s dry. You gotta have seasoning. That 5 spice I was talking about, that’s actually different from place to place. Each one representing the flavors that the chef wanted. It’s actually the same in India. Curry powder is not a real thing. Each area and household has their own spice mix.
For me personally, while I agree with you that you should make your own, I tend to just use Cajun seasoning. Dunno, it’s cheap and readily available. But you keep doing you. Personal spice blends is absolutely the way to go.