There are several factors that go into a great sandwich:
1. The ingredients
You want to make sure that some thought has been given into to the flavours. I sort of think about sandwiches like a piece of music. Let me explain myself - the mayo or cheese is the bass line. The bread is the percussion that holds everything together. Then there are the filler instruments playing the mid range notes like the veggies. And for the melody, that's where that sharper taste like a signature sauce really identifies the sandwich. Then you have to make sure you've got the right balance of each of those 'instruments.' You can't have the bass so loud that you can't hear the melody.
Did my analogy make any sense?
2. The order of the ingredients
You can't just throw a sandwich together - you have to consider in what order you'll be tasting the flavours when you take a bite. Those of you who understand this know the frustration of being served a burger where the top and bottom bun are switched.
There isn't really a three but lists usually have at least three items ...
The sandwich you see above is the Pear, Blue Brie, Prosciutto and Walnut sandwich. If it were a symphony, it would be Beethoven's 9th.
So there you have it, the best sandwich I've ever had at Finch's on Pender and Homer. Check it out if you have a chance, you will surely be impressed.