- Into a medium saucepan over medium heat, add butter. When butter is melted, add onions. Sauté 2 minutes, until onions are softened. 
- Add salt and oregano. Continue cooking 2 minutes more, stirring frequently, until onions are just beginning to turn golden in color. 
- Add garlic and cook for an additional 1 minute. 
- Pour in crushed tomatoes and add sugar. Increase heat to medium high for 1-2 minutes, just enough to heat through. Reduce heat back down to low and simmer 10 minutes. 
- Remove from heat then stir in olive oil and basil. 
- Use salt, pepper, and red pepper flakes to adjust seasoning to taste.