Heat a tablespoon of olive oil in a large heavy-based pot on MED-HIGH. Add the ground pork and beef. Break the meat up with a spoon. Cook for 10–15 minutes, until it is browned.
Remove the meat from the pot. Drizzle in the rest of the olive oil. Add in the chopped onions, celery, carrots, and garlic. Sauté for 5–8 minutes.
Return the meat to the pot along with the tomato paste, crushed tomato, beef stock, Italian herbs, and a pinch of salt and pepper. Stir it all together. Cover it with the lid, and bring to a boil. Once the pot is boiling, turn down the heat and let it simmer for 45 minutes.
When there’s 15 minutes left for the meat, preheat the oven to 350°F. In a non-stick skillet or a saucepan, melt the butter. Whisk in the flour until the mix becomes slurry smooth.