Prepare the tomatoes: Slice the tomato into thick rounds and set aside.

Assemble the sandwiches: Spread mayonnaise evenly on all four slices of bread.

Layer the tomatoes: Place the tomato slices on two of the bread slices. Season generously with salt and black pepper.

Close the sandwiches: Top with the remaining bread slices, mayo-side down.

Serve immediately and enjoy the fresh, simple flavors!