Swirl a bit of oil into a deep skillet—just enough to coat the bottom of the pan. Heat over medium-high flame until shimmering. Add the beef, breaking it up into small bits with your fingertips. Season the meat with salt and pepper. You might need to do this in batches as to not overcrowd the pan (remember to re-season each new batch of meat). Cook, stirring every couple of minutes, until browned all over. Using a slotted spoon, transfer to a bowl.

Lower the flame to medium-low. Add the onion to the pan. Sauté until slightly softened and golden.

Pour in the wine, and use a spoon to scrape up any browned bit from the bottom of the pan. Increase the heat to medium-high. Cook until the wine reduces by half.

Stir in the tomatoes, sugar, and butter. Add the beef back to the pan. Season with salt and pepper. Bring to a boil, the reduce heat to the lowest setting possible. Let the sauce simmer for 3 to 4 hours, until meltingly tender. If not ready to serve when done, you can transfer the sauce to a slow cooker, and keep it on the warm setting until ready to serve.