A hot bowl of soup when you feel a cold coming on is so soothing. As my friend, Viktorija would say, "Use whatever veggies you have." or "Relax"! Take her advice- I know I should!
In French cooking, carrots, celery, and onion minced and mixed together can be the main part of your broth- Mirepoix if you will. If you are lucky enough to have leftover chicken on hand, or a whole, uncooked chicken, you can use it to make the stock. If not, simply chop equal parts carrots, onions, and celery (1 cup of each if you need exact measurements) and throw it all into a pot with some olive oil coating the bottom (1 tsp or so). Stir, on medium heat, until the onions are fragrant. The veggies will not be 'done' yet, but go ahead and add 4 cups (1 liter) of boiling water or (preferably) broth or stock. I use bullion cubes to make my broth when I'm lazy, or if I'm industrious, I create stock from scratch by boiling a whole chicken with a bunch of veggies, straining this completely, stripping the meat off the chicken bones and then using the strained broth at this point in the process (add the cooked chicken pieces at the last minute, if desired). Bring the mixture to a boil, stirring occasionally and then time the addition of any other veggies you like, such as broccoli (takes 5 minutes to cook), cauliflower (3 minutes), sweet peppers or herbs (add at the last minute). If you are adding potatoes, I recommend doing so when you saute the carrots, celery, and onion in the first step, or right after you bring your mixture to a boil. If you are crazy about veggies not being over cooked, you can also start your stock/broth boiling, add potatoes, cook for 15 minutes, then add the carrots, celery, and onion and cook for another 10 to 15 minutes. However, I really prefer the onions sauteed a bit with the olive oil(and a pinch of salt) at the start, so that they get a bit caramelized.
Serve, piping hot, with Parmesan cheese or a swirl of extra virgin olive oil on the top along side some homemade French bread. If you want your soup to be a noodle soup you can add the pasta (preferably something small like ditalini) as soon as your mixture has come to a boil after you've added the broth or stock or water. If you only use boiling water you will definitely need to salt your soup!