10. Use a very large pot to heat oil (high heat). Wait for it to shimmer, then add the onions, carrots, and celery; cook until the vegetables start to sweat (don’t wait for them to become brown).
11. Add the ground beef, using a wooden spoon or spatula to break up the meat into small pieces.
12. Cook the beef, until half of the liquid has evaporated (stir occasionally).
13. Add the tomato sauce, tomato paste, chicken stock, salt, and pepper; stir to break the lumps.