Juicy and Tender Meatballs

• From Serious Eats J Kenji-Lopez. This was absolutely delicious and so moist --they are big meatballs and delicious. Only substitute I made was what I had on hand was 1/2# ground pork and 1/2# ground veal. Yummo!

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• 1 packet unflavored gelatin (optional, see note)
• 1/2 cup homemade chicken stock or low-sodium broth (optional, see note)
• 4 ounces fresh white bread, crusts removed and bread cut into 1/2-inch cubes (about 2 unpacked cups)
• 1/3 cup buttermilk, plus more as needed
• 1 medium onion, minced
• 8 cloves garlic, finely minced
• 2 ounces grated Parmigiano-Reggiano, grated, plus more for serving.
• 1/2 cup loosely packed fresh parsley leaves, minced
• 4 teaspoons kosher salt (18 grams; see note)
• Freshly ground black pepper
• 3 ounces fatty pancetta, finely minced (see note)
• 4 large egg yolks
• 1 teaspoon dried oregano
• 1 teaspoon ground fennel seed
• 1 pound ground beef (at least 25% fat)
• 1 pound ground pork (at least 25% fat)
• 5 cups tomato sauce, such as Quick and Easy Italian American Red Sauce, The Best Slow Cooked Tomato Sauce, or The Best Fresh Tomato Sauce

1. 1.
   In a heatproof measuring cup, sprinkle gelatin all over surface of stock and let stand for 5 minutes (if not using stock and gelatin, proceed to Step 2). Microwave stock, stirring once or twice, until gelatin completely dissolves, about 2 minutes. Pour stock into a wide heatproof bowl and refrigerate until fully set, about 30 minutes.
2. 2.
   In the bowl of a stand mixer, combine bread with buttermilk, tossing to coat. Let stand, tossing occasionally, until bread is completely moist, about 10 minutes. Squeeze bread between your fingers or mash with a spoon to make sure there are no dry spots; if there are dry spots that refuse to moisten, add more buttermilk 1 tablespoon at a time until bread is moist throughout.
3. 3.
   Add onion, garlic, Parmigiano-Reggiano, parsley, salt, pepper, pancetta, egg yolks, oregano, and fennel to bread/buttermilk mixture. Finely mince gelled stock, if using, and add.
4. 4.
   Set mixer bowl in stand mixer and attach paddle. Starting at low speed and gradually increasing to medium-high speed, beat bread mixture until thoroughly blended, stopping to scrape down sides as necessary. Add 1/3 each of the beef and pork and beat at medium-high speed until thoroughly blended with bread mixture.
5. 5.
   Remove bowl from stand mixer and add remaining beef and pork. Using a clean hand, gently mix meatball mixture, teasing apart ground meat with your fingers, just until ground beef and pork and thoroughly distributed throughout; avoid mixing any more than is necessary for even distribution.
6. 6.
   Preheat broiler and set oven rack in upper position. Line a rimmed baking sheet with aluminum foil. Form meatball mixture into handball-sized balls and arrange on prepared baking sheet; you should be able to make about 10. Broil meatballs until browned on top, about 7 minutes (browning times can vary dramatically, depending on oven broiler strength).
7. 7.
   Heat tomato sauce in a medium pot until simmering and add meatballs. Simmer until meatballs are just cooked through and register about 145°F on an instant-read thermometer, about 10 minutes.
8. 8.
   Serve meatballs, spooning sauce all over and grating more cheese on top.