Toast the bread slices until golden brown and crispy, then set aside.
Spread a thin layer of mustard on one side of each bread slice to add tangy flavor.
Layer the turkey slices evenly on one of the bread slices, creating a layer of savory meat.
Slice the avocado in half, remove the pit, and either thinly slice or mash it. Spread or layer the avocado generously over the turkey.
Place the second slice of bread on top, mustard side down, aligning the layers nicely.
Gently press down on the sandwich to help everything stay together, then slice in half diagonally for easy eating.
Serve immediately, enjoying the crispy bread and creamy avocado with each bite.