For the matzo balls:

Heat the chicken fat over medium heat in a small pan. Add the chives and cook for 30 seconds. Set aside to cool slightly.

In a large bowl, add the eggs, dill, seltzer, sugar, and salt and pepper and whisk until combined. Add the matzo meal and the chicken fat/chive mixture and stir to combine. Cover well and refrigerate for at least 8 hours and up to 24 hours.

Bring a large pot of salted water to a boil over medium heat. Form the matzo mixture into 8 equal size balls, about 1 3/4 ounces each, add to the water, reduce the heat to simmer, cover and cook until very tender, about 1 hour and 20 minutes. Remove with a slotted spoon to the pot with the chicken stock and cook for 5 minutes before serving. Ladle the soup into individual bowls and serve.

For the chicken stock:

Combine all ingredients in a large stockpot and add enough cold water to cover by 2-inches. Bring to a boil, over medium heat, then reduce the heat to low and simmer, skimming the scum from the stock with a ladle, every 15 minutes, for 3 hours. Strain into a large bowl and discard the solids.

Transfer to a large saucepan and cook until reduced by half. Add the roasted jalapenos for the last 10 minutes or of simmering, then remove. Season with salt, pepper and freshly chopped dill.