Butter your bread slices on both the sides and toast them either on a griddle or in a air fryer or in the oven, until golden. You can also skip the toasting step and use fresh bread if you prefer soft sandwiches.
Toast On a Griddle/ Pan: Heat a pan and place your buttered slices of bread over it. On a medium heat, toast until golden and crisp, turning to the other side when one side is done.
Toast in Air Fryer: Place the buttered slices in the air fryer basket or rack. Air fry for 2 to 3 mins at 360 F or 180 C. 3 mins will give you very crisp toast.
To a mixing bowl add the veggies, herbs, mustard, black pepper, red chili flakes, salt and yogurt. Leave out any optional ingredients you prefer not to use.
Scoop off the filling to the toasted bread and spread it all over. Cover with another slice & press down. If you are using untoasted bread, spread some softened butter first and then spread the yogurt filling. This prevents your sandwiches from turning soggy.
Slice your yogurt sandwich and serve right away or within 2 hours. If you keep them longer at room temperature they are likely to turn sour.
Scoop the yogurt filling to the buttered bread and cover. Grill it in the sandwich maker. For this use very cold yogurt. Heat destroys good bacteria in the yogurt so do not grill for too long until the yogurt becomes hot.