"The End of the World and Hard-Boiled Wonderland"
I'm probably pretty critical of sandwiches, just like I am of sofas, but this sandwich easily passed my standards.
The bread was fresh, firm, and cut with a sharp, clean knife.
It's something that's often overlooked, but having a good knife is absolutely essential to making a good sandwich. No matter how good the ingredients are, if you have a bad knife you won't be able to make a good sandwich.
The mustard was good, the lettuce was firm, and the mayonnaise was homemade or nearly so.

"A sandwich made by my granddaughter with a good knife."
In this scene, the protagonist eats more than two-thirds of the "five or six plates' worth" of ham, cucumber, and cheese sandwiches made for him by the old professor's granddaughter. The protagonist is picky about sandwiches, but he believes a "sharp knife" is essential for a "good sandwich." He chose a knife from the German company Henckels, as it can be inferred that the nail clippers he gave the woman as a gift were from that company.