There are so many basic recipes that can be improved with a simple change of ingredients, like a homemade stock for tastier gravy, vinegar instead of oil with fresh tomatoes, and a tin of black beans for richer chocolate cake. When it comes to tomato sauce, many would argue that buying it from the supermarket warrants the most delicious pasta dishes. But chefs, including 101 Cookbooks founder Heidi Swanson, would disagree. She says that just one ingredient can transform a humble tin of crushed tomatoes into a "bright and juicy" sauce. Heidi's secret is simple: lemon zest brightens tomatoes without making the sauce too lemony or acidic. | 
