Heat a saucepan over medium-high and add the butter.
When the butter begins to bubble, add the ground beef and chopped onion.
Cook, breaking up the beef, until the meat is nicely browned and the onion is soft and fragrant, about 5 minutes.
Add the can of whole peeled tomatoes and the Italian herb spice mix. Break up the tomatoes with a potato masher or large ladle.
Bring to a gentle bubble, then reduce heat to low and simmer, uncovered, for 45 minutes, stirring occasionally.
Season with salt to taste and serve.
