How to Make It
In a medium bowl, mix the matzo meal with the baking powder and the salt. In a small bowl, whisk the eggs with 3 tablespoons of the schmaltz. Gently mix the egg mixture into the dry ingredients. Using a 1 1/2-ounce ice cream scoop, portion into rough balls and refrigerate for at least 30 minutes.
Meanwhile, in a medium saucepan, heat the remaining 1/4 cup of schmaltz. Add the garlic and cook over moderately high heat until golden and fragrant, about 1 minute. Add the onions and celery and until translucent, about 2 minutes. Add the chicken stock and bring to a boil. Reduce the heat and simmer for 30 minutes. Keep warm.
Bring a large saucepan of water to a boil. Using greased hands, roll the chilled matzo into even balls and drop into the boiling water. Cover and boil until cooked through, about 30 minutes (you might have to cut into one ball to check). Using a slotted spoon, transfer the matzo balls to a plate.
Remove the broth from the heat and whisk in the fenugreek and turmeric; season with salt. Divide the matzo balls between shallow bowls (about 2 per person) and ladle the soup over the top; serve.