I buy the boxed matzo ball flour and follow the recipe for making the balls on the back. We are veggie, so I don't add chicken fat or use chicken broth, both of which would work great in this soup if you eat chicken.
For the soup I do one of two things:
For a more regular/traditional soup I saute onions in some olive oil. Add in some chopped carrot, saute for a bit. Add in some chopped celery, then broth. Bring to a boil, reduce heat to a simmer, add the matzo balls and simmer for 15-20 min, until carrots are soft. I sprinkle a bit of fresh chopped parsley when I serve the soup.
Or I make a multi-veggie soup, w/carrots, celery, broccoli, garbanzo beans, any other veggies I have on hand (asparagus, peas etc...), and add the matzo balls to this. My whole family loves this.