First, make the matzah ball mix. In a medium bowl, whisk together eggs, olive oil or schmaltz, and sparkling water. Then stir in matzah meal, onion, baking powder salt, pepper, cumin and cilantro. Do not over-mix. Refrigerate for at least 30 minutes so the mix is not as sticky.
Meanwhile, start your soup. Put the chile in a small heatproof bowl and cover with boiling water. Let the chile soak until soft, about 15 minutes. Remove chile and reserve soaking liquid.
In a large Dutch oven, heat olive oil or schmaltz over medium heat. Add in onion with ¼ teaspoon salt and sauté for 5 minutes, or until softened. Then add in jalapeño and garlic and sauté for 2 more minutes. Add in cumin, smoked paprika, chili powder, black pepper and remaining salt and sauté while stirring for 1 more minute.
Transfer to a blender with 2 cups broth, half of the tomatoes, the pasilla chile and ½ cup soaking liquid. Blend. You can also use an immersion blender and blend right in the pot.
Place mixture back in the pot and add in remaining broth and tomatoes.
Matzah ball time! Form matzah ball mix into about 15 1-inch balls. Bring soup to a simmer and place balls in the stock. Cover and simmer for about 30 minutes, or until balls float and are cooked through. You can also cook the matzah balls separately in water or chicken broth.
Then add chicken and cook a few more minutes uncovered until chicken is warm. Season with salt and pepper to taste. Serve hot with cilantro, lime, avocado and jalapeño slices.