2 packages of individually portioned Udon noodles.
If you don't use the included seasoning packets, 2 cubes of Vegetarian bouillon and water to cover noodles and fill a soup pot a little more that half way, or broth in the same quantity if you don't like bouillon.
Soy Sauce to taste, maybe a splash.
Rice Wine Vinegar to taste, also a splash or two.
Ginger, your choice of fresh sliced or chopped. You can also use dried or candied slices. I like to use Christopher Farms jarred ginger.
Something sweet, like agave or raw sugar, just a touch. If you used candied sliced ginger there is no need to sweeten any further. If you're not a vegan used honey.
Black and white pepper to taste.
After bringing the stock and noodles to a boil, turn down the heat to warm and add:
1 C baked tofu slices or cubes.
3 fresh red chiles, sliced. Seed if you don't like searing heat.
1/2 small head of napa cabbage, sliced.
2-4 C small baby bok choy, well rinsed and halved.
1 box of sliced mushrooms, cooked separately or fresh.
Bean sprouts, for topping when you serve the soup.
This soup does not keep well overnight. The noodles get soggy and the vegetables wilt. If you are making this only for yourself, make the stock ahead of time and freeze the extra. Buy and prepare less of the other ingredients and only add what you are going to eat at that time to the stock and save the rest for later. I know it's hard to buy fresh veggies in small quantities, but napa keeps well if you peel the outer layers and save the heart. Baby bok choy will keep longer if you don't wash it until you're ready to use it. The noodles will keep well; some brands are shelf stable. Chiles keep well in the fruit bowl and baked tofu can always be washed and scrubbed by hand if it gets a little slimy.