To Make the Matzo Balls:In a small bowl, combine the matzo meal, salt and pepper.In a separate mixing bowl, add the whisked eggs, seltzer, and schmaltz or olive oil and whisk together. Add the dry mixture to the wet mixture and stir to form a thick, sticky paste. Chill, uncovered, for at least 30 minutes.Lightly oil the palms of your hands and gently roll the mixture into balls avoiding compressing them too much. They can be anywhere from 1 to 2 inches in diameter depending on your preference. Keep in mind they will expand as they cook.
To Make the Soup:Pour the chicken broth into a large pot. Add the carrots, celery, salt and pepper. Bring to a boil. Reduce it to a simmer and carefully lower the matzo balls into the broth. Adjust the heat to keep the broth going at a steady simmer but do not let it boil. After the matzo balls are all in the broth, gently move them around a bit to prevent them from sticking to each other. Then cover the pot with the lid and simmer gently for 30-40 minutes. Periodically turn the balls over to ensure they're cooking evenly. Add salt and pepper to taste. Divide the matzo balls between soup bowls and ladle the broth over them.Sprinkle with chopped fresh dill (my favorite) or parsley. Serve immediately.