I mostly make this with chicken stock of the home-made variety, although for years I made it using Massel's chicken stock powder, 'cause my sister's a vegetarian. If I'm feeling extravagant, I'll also add actual chicken to it. So it's not out & out veggie soup, but eh.
I cook in fairly large batches, but this is easy to make, say, 4 servings of; just scale down the ingredients. It doesn't freeze all that well, though - the texture of the veggies tends to get a bit weird. Anyway, I'm very good at over-catering, so I can't swear how many servings the following instructions make, but it's a large pot of very tasty soup - at least 12 servings or so
2-3L chicken stock, 2-3 carrots, 1 head of cauliflower, 1/4 of a head of cabbage, 1-2 bunches of bok choy, 1-2 stalks of celery, 4 tsp minced ginger, 6 cloves of garlic (peeled but whole), soy sauce & sweet chili sauce to taste, 2tsp turmeric, 2-3 small cakes of rice noodles, 4-5 chicken thigh fillets, cut into strips.
The vegetable combination is pretty flexible (I don't like celery, & often omit it; if you're using stock cubes/powder, it might be an idea to simmer an onion in the stock to flavour it up a bit) and the flavourings are hard to measure 'cause the soup works best flavoured to taste. The ideal combination balances the heat of the turmeric & chili with the sharpness of the ginger, with the soy sauce rounding out the flavour. You really do have to add, taste & modify with the flavourings in this, so under-estimate at first & keep adding more of each in turn until it seems right to you.
So. Take the stock, bring to a low boil. Chop the veggies into whatever shapes you prefer, but don't cut them too small - the carrots work well in 1cm-ish thick rounds, the cauliflower in medium florets. You're going to cook them slowly, so the pieces need to be big enough not to fall apart, but small enough to soften through.
Add the carrots, celery & chicken to the stock, cook for 5 minutes at a very gentle simmer.
Add the garlic cloves, ginger, turmeric & cauliflower, maintain the simmer until the cauli has nearly softened.
While the veggies are simmering, soak the rice noodles in hot water. Add the noodles, cabbage, sweet chili & soy sauce, simmer for a couple of minutes - the cauliflower & cabbage should be cooked, but not mushy.
The bok choy will cook very quickly, so only add it at the very end - if you're making enough of this for leftovers, it's best to add the bok choy to each serving so it doesn't over-cook as the soup cools.
The flavour of the soup will change as the various veggies cook, and you don't really get an accurate idea of its character until you've added the cabbage and noodles, so it doesn't hurt to be conservative with the spices & stuff, and add more at this point if you need it.
You should be able to taste the characteristics of each flavour, but they should also be balanced - it shouldn't taste like GINGER soup, but you should definitely be able to identify the ginger in the flavour. Adding a little of the noodle-water also improves the flavour, but don't add more than a couple of ladles of it - you don't want it to taste starchy.