Heat the oil in a saucepan. Saute the onions over medium heat until softened. Add the garlic and oregano and cook for another minute, adjusting the heat if needed so that the garlic doesn’t burn. Add the tomato paste and cook for 2 minutes, stirring.
Pour in the canned tomatoes and add the sugar, salt and cracked black pepper. Simmer for 30 minutes, stirring occasionally. You can put a lid on it, keeping it ajar, if it is splattering. Taste for seasoning and add more salt if needed.