In a medium bowl, mix the matzo meal, eggs, chicken fat or oil, 1/4 cup of chicken broth or water, salt, and black pepper. Stir until well combined and refrigerate for at least 30 minutes.
Bring 8 cups of chicken broth to a boil in a large pot. Reduce to a simmer and add the sliced carrots and celery. Cook until the vegetables are tender, about 20 minutes.
With wet hands, form the matzo ball mixture into 1-inch balls. Gently drop them into the simmering broth. Cover and cook for 30-40 minutes, or until the matzo balls are cooked through and light.
Serve the soup hot, with matzo balls and vegetables in each bowl.