In a large saucepan, melt the butter and olive oil over medium heat. Add the onion and cook, stirring occasionally, until softened. Stir in the garlic and cook until just fragrant, 30 seconds to 1 minute. Add the tomatoes, oregano, red pepper, basil, sugar, and salt. Once the mixture is boiling, reduce heat to low, until barely simmering, and cook until reduced by half, 30-60 minutes.