Prepare the Matzo Ball Mixture: In a mixing bowl, whisk together eggs, schmaltz (or oil), water, salt, and pepper. Stir in matzo meal and fresh herbs (if using). Mix until combined, then cover and refrigerate for at least 30 minutes.
Make the Broth: In a large stockpot, heat olive oil over medium heat. Add onions, garlic, carrots, and celery, and sauté for 5 minutes. Pour in chicken broth, add bay leaves, and bring to a gentle simmer for 30 minutes.
Shape the Matzo Balls: Wet your hands and roll the chilled mixture into 1-inch balls. Don’t pack too tightly, this keeps them fluffy.
Cook the Matzo Balls: Gently drop the balls into the simmering broth. Reduce heat to low, cover, and cook for 30–35 minutes until the dumplings are cooked through and puffed up.
Finish the Soup: Remove bay leaves, taste the broth, and adjust seasoning with salt and pepper.
Serve: Ladle the soup into bowls, making sure each serving includes carrots, celery, broth, and 2–3 matzo balls. Garnish with fresh dill or parsley.