Just like the pizza sauce, this is a great recipe to make when you have excess fresh tomatoes. And again, you can use tinned whole tomatoes. If you are wondering why your passata goes orange, passata and other tomato-based sauces will go orange during the cooking process when the tomatoes aren’t in season. For a delicious red sauce, purchase tomatoes in season and make batches to store or freeze. The other great thing is that buying vegetables when they're in season is also cheaper.