Brown the ground beef in a large skillet over medium-high heat, breaking it up with a wooden spoon, until no pink remains, about 7 to 10 minutes; spoon off most of the grease if needed, leaving a couple tablespoons behind.

Stir the diced onion into the browned beef and cook for another 3 to 5 minutes, until the onion begins to soften and looks translucent around the edges.

Scrape the beef and onion mixture into a 5- to 6-quart slow cooker, including the browned bits from the skillet.

Pour in both cans of tomato sauce and stir in the kosher salt and black pepper if using; the mixture should look thick and meaty.

Cover and cook on LOW for 4 to 5 hours or on HIGH for 2 to 3 hours, until the onions are completely softened and the sauce is rich and fragrant.

About 30 to 40 minutes before serving, stir in 1 1/2 cups water and the dry elbow macaroni, making sure the pasta is mostly submerged; add up to another 1/2 cup water if needed.

Cover and cook on HIGH for 20 to 30 minutes, stirring once halfway through, until the macaroni is tender but not mushy; add a small splash of water if the sauce thickens too much.

Taste the goulash and add more salt or pepper if needed, then serve hot with a saucy consistency and tender elbows.