Step 1

Heat the olive oil in a large pan over medium heat. Add the onions and sauté until lightly golden, 2 to 3 minutes. Add the garlic and fry another minute.

Step 2

Add the ground beef; fry until fully cooked and no pink shows at all in the meat (about 8 minutes). Add the oregano and tomato paste and mix with the meat.

Step 3

Add the tomatoes, parsley, and bring to a boil. Season with the salt and pepper. Reduce the heat to low, and cook for at least 15 minutes (you can cook longer for a deeper flavor).

Step 4

In the meantime, cook the spaghetti according to the package instructions. Drain and serve topped with the sauce and cheese (if using).