Spaghetti Sauce

1 tbsp. unsalted butter
2 tbsp. grated onion
Pinch of dried oregano
¼ tsp. salt
1 clove garlic, minced or pressed
1 (14.5 oz) can crushed tomatoes (I used diced and then blended the sauce after it was cooked)
Pinch of sugar
2 tbsp. fresh basil leaves, coarsely chopped
1½ tsp. extra-virgin olive oil
Ground black pepper

Melt the butter in a medium saucepan over medium heat. Add the onion, oregano, and salt. Cook, stirring occasionally, until the liquid has evaporated and the onion is golden brown, about 5 minutes. Add the garlic and cook just until fragrant, about 30 seconds. Stir in the tomatoes and sugar and increase the heat to medium-high. Bring the mixture to a simmer, then lower the heat to medium-low and continue to simmer until reduced to about 1¼ cups, about 25 minutes. Off the heat, stir in the basil and oil. Season with salt and pepper to taste.