San Marzano Tomato Sauce

In a 3-quart saucepan, heat the olive oil over medium heat. Add the onion and cook until soft and light golden brown, 8 to 10 minutes. Add the thyme, tomatoes, and juice and bring to a boil, stirring often. Lower the heat and simmer for 30 minutes until as thick as hot cereal. Season with salt and pepper.