Pour tomatoes and juice into a large bowl. Using your clean fingers, squish the tomatoes to break them up.

In a medium pot or Dutch oven, over medium-high heat, add ground beef. Cook until the beef is almost fully cooked, which should take around 7 to 10 minutes. During this cooking time, use a spatula or spoon to break up the meat into small pieces. 

Once the beef is cooked, add chopped onion and saute for 3 to 5 minutes or until the onions are softened. Lower the heat to medium, add garlic, and cook, stirring occasionally, for another minute.

Add a teaspoon of tomato paste and cook, stirring for 1 minute.

Add the crushed tomatoes and stir everything together. At this point, you can use a potato masher to mash the tomatoes up even more for a smoother consistency. 

Add chicken stock, salt, sugar, and red pepper flakes to the sauce, and simmer for 50 to 60 minutes.

Add diced basil and simmer for an additional 5 minutes to complete the sauce.

Store in a sealed container in the refrigerator and warm in a pot on the stove or in a bowl in the microwave.