Wash the arugula thoroughly and remove excess water.
Slice the tomato and avocado.
Cut the ciabatta bread in half and lightly brush with olive oil.
Lightly toast the bread in a pan or toaster.
Spread mustard or your preferred sauce on one side of the bread.
Layer cheese, avocado, tomato, and arugula in order.
Season with salt and pepper.
Close with the other piece of bread to complete the sandwich.