The primary ingredient in traditional sarnies, which are British sandwiches, is bread. Sarnies are generally made with two slices of bread filled with various ingredients such as meat, cheese, vegetables, or spreads. Common fillings include ham and cheese or cucumber and cream cheese. The simplicity of the sarnie makes it a popular choice for a quick lunch or snack. Different regions in the UK may also have their own variations and specialties, but the foundational component remains the bread, highlighting the versatility and cultural significance of sandwiches in British cuisine.