It's like an episode of Ready, Steady, Cook crossed with MacGyver.
You've got a handful of random ingredients, a mason jar and a kettle....your time starts NOW! I'm either making lunch or defusing a bomb.
I like to carry it in the mason jar and then put in a bowl for eating. Is it the best soup I've ever had? No. Is it quick and easy and filling? Yes. All you need to add is boiling water. I could probably prep several jar on the go just to grab to take to work, but I only do one at at a time. This is mainly because I have only two mason jars (one to wash and one to use) and a British sized fridge, which is to say SMALL. If I put a week's worth of jars in my fridge, there would be no room for anything else.
I make my soup with noodles, peas, carrots and mushrooms with some tamari/soy sauce and vegetable stock powder.
I buy these brown rice vermicelli noodle nests. I use half a noodle nest for every meal. If wheat is not an issue, ramen noodles (sans the spice packet) would be ideal. I do most of my prep the night before, but add the mushrooms in the morning as it stops them going brown. I matchstick a whole carrot and store it in a jar covered in water and just pull out what I need each night when I do prep to save time
Some recipes I saw used uncooked vegetables and noodles and let the boiling water on the day of eating do the cooking. I found it meant my soup got cold, so I pre-cook everything but the mushrooms so I can eat it hot. I also prefer to add my broth powder right before I add the boiling water and not in the jar. I find if I put it in the jar it clumps. Nobody wants clumpy soup. So I carry a small tub of broth powder (I use my homemade stock powder, but you could use something like Marigold.)
Mason Jar Soup
The night before:
1/4 cup frozen peas
1/4 cup carrot cut into thin matchsticks
half a noodle nest
Put ingredients into a pot and cover with boiling water for as long as the noodles need to cook. Mine take four minutes. Then drain and run under cold water. Add to jar. Add 1 TB tamari/soy sauce. Put the jar in your fridge.
In the morning add:
1 sliced mushroom
Take it to work. When you are ready to eat, add the contents of your jar to a bowl with 2 tsp instant broth powder and fill up with boiling water. Then eat.
Easy as that. You could probably get creative and add all sorts of stuff, but this is the tried and true one I have been doing. If I come up with a new version, I will report back.