Make the meatballs: In a mixing bowl, combine the breadcrumbs with the beaten egg and parmesan. Let the mixture sit for 10 minutes. Add the sausage, beef, tomato paste, garlic, parsley, salt and pepper and mix by hand. Use a tablespoon to make small meatballs and lay them out on a parchment lined baking sheet.
Broil the meatballs. Set an oven rack in the top ? of the oven and turn the broiler on high. Broil the meatballs for 6-8 minutes, until browned. Remove the meatballs from the oven and set aside.
Render the pancetta. Heat the olive oil in a 4-5 qt dutch oven over medium heat. Once the oil is hot, add the pancetta and cook for 6-7 minutes, stirring often, until the pancetta is crispy. Use a slotted spoon to transfer the pancetta to a small bowl.
Build the soup. Add the onions, carrot, and celery to the pot and saute for 3-4 minutes, until the vegetables are soft. Stir in the dried oregano and basil and cook for another minute. Pour in the chicken stock and bring to a gentle simmer. Add the meatballs and crispy pancetta, cover, and simmer for 10 minutes. Stir in the pasta and simmer until pasta is tender, about 8 minutes.
Finish the soup. Stir in the baby kale, lemon zest, and lemon juice and simmer just until the greens are wilted. Season to taste with salt and pepper. Ladle the soup into bowls and top with grated parmesan.