It isn’t exactly what you’re asking for, but here’s how I prepare those instant lamen packages when I don’t have frozen broth:
brown the meat in the pot that I’m going to use with the lamen. Reserve.
add ginger, sesame seeds, and brown sugar to the pot. Let them caramelise a bit, and add the rest of the seasoning (garlic, soy sauce, pepper sauce, MSG, etc). Then water.
add vegs and let them cook. Aside cook the noodles and probably boil some eggs.
assemble everything.
So the “broth” is mostly the juice of the vegs and meat, soy sauce, vinegar and condiments. It isn’t exactly flavourful, but good enough.
If I had to improve it I’d probably use a chicken bouillon (for any land meat) or powdered dashi (for fish lamen). And perhaps half of a package of flavourless gelatine, for texture. (Some people might use miso instead. My body does not handle it well so I don’t even have it, but it’s an option for you.)
Sometimes I also add half a sheet of nori, as kombu is hard to find where I live. Taste-wise it’s good, but be aware that you’ll get some “nori fragments” at the bottom, I don’t mind but the texture isn’t exactly great.