01 -
Gently cook the diced onions in 14 grams of butter over low heat until just translucent, ensuring they remain white and do not caramelize.
02 -
Increase heat to medium-high, add ground sirloin, salt, and black pepper to the onions, and cook until the beef is browned, tasting for seasoning and adjusting salt as needed.
03 -
Stir in diced tomatoes and celery, cover with a lid, and simmer on medium-low heat until the celery is softened, about 15 to 20 minutes.
04 -
Turn off the heat, mix in the remaining butter to enrich the sauce, then spoon over freshly cooked spaghetti and serve immediately.