The main ingredient in a traditional tart typically consists of a pastry crust made from flour, butter, and water. The crust serves as a base to hold a variety of fillings, which can be sweet or savory. Sweet tarts often feature fruit, custards, or chocolate, while savory tarts might include vegetables, cheese, or meats. The preparation involves rolling the pastry and baking it before adding the filling. The versatility of tarts makes them a popular choice in various cuisines, and they can be found in many forms worldwide, reflecting local ingredients and preferences.