Making a Turkey Avocado Sandwich is straightforward and enjoyable. Follow these step-by-step instructions for a delicious result:

1. Prepare Ingredients: Gather all required ingredients and have them ready on your countertop.
2. Mash Avocado: In a mixing bowl, smash the ripe avocado with a fork. Add lemon juice, salt, and pepper. Mix well to incorporate the flavors.
3. Spread Avocado: Take four slices of whole-grain bread and spread a generous amount of the smashed avocado mixture on each slice.
4. Layer Turkey: On top of the avocado spread, layer the sliced turkey breast evenly across the bread.
5. Add Vegetables: Next, place fresh spinach leaves, followed by tomato slices and red onion on top of the turkey.
6. Optional Spread: If desired, spread mayonnaise or Greek yogurt on the remaining four slices of bread for added creaminess.
7. Top Sandwiches: Place the remaining slices of bread, spread-side down, on top of each sandwich to complete them.
8. Cut Sandwiches: Carefully slice each sandwich in half diagonally to make them easier to handle and serve.
9. Serve Immediately: Enjoy your Turkey Avocado Sandwich right away for the best flavors.

These instructions will help you assemble a Turkey Avocado Sandwich that is both delicious and visually appealing.