Toast the slices of bread until golden brown and crispy to your liking. This provides a sturdy base and added crunch.
Cut the avocado in half, remove the seed, and scoop the flesh into a small bowl. Use a fork to mash it until smooth and creamy, with slight chunks for texture.
Spread a generous layer of mashed avocado onto one side of each toasted bread slice. Cover the surface evenly with the creamy mixture.
Lay the leaf of lettuce on top of the avocado on one slice of bread.
Place the sliced turkey evenly over the lettuce, overlapping slightly if needed.
Add a small spoonful of mustard on the second slice of bread with avocado, then sandwich it on top of the fillings, creating a complete sandwich.
Gently press down on the sandwich to compact the fillings slightly, then cut diagonally or in half for easier eating.
Serve immediately to enjoy the crisp toast, fresh ingredients, and creamy avocado together.