I really think it's got to be the sausage that gives this soup it's flavor. I've made vegetable soup different ways, but this one has had the best flavor.
1/2 to 1 pound mild ground sausage
1/2 lb lean hamburger
6-8 C hot water (enough to cover the raw vegetables)
5-6 bouillon cubes
1 onion
4 stalks celery
2 or so cups chopped carrots
8 or so cubed red potatoes
1 or 2 cans of corn
You can add other veggies you have on hand that you like such as cauliflower, green beans, peas, etc.
1 can tomato paste
seasonings you like - I've used things like garlic, basil, an all seasoning without salt, garlic salt or seasoning salt. (Not all of these at the same time though)
Saute the meat til it's very well browned. You want to get that nice browning that is going to give your liquid a lot of flavor.
Add chopped onions after meat is well browned and cook til soft.
Start adding your other chopped raw veggies, then cover with hot water. I do the water hot so it speeds up the cooking time. Add your bouillon cubes.
Let the veggies cook about 15 to 20 minutes til soft.
Mix your tomato paste with some hot water prior to adding it to your soup so it's easier to blend it in. Add your corn and any other veggies that are pre-cooked, such as frozen peas.
Add your seasonings any time you want. Mine usually go in last.