This is a very interesting yet harsh job sim, and I love it! I think my experience was drastically better than others just with the knowledge of the intended perfect play requirement, and that sweaty carefulness made this game feel great. Aside from gameplay, I do like the simplicity of the sandwich itself, and also the cute monster customers you are serving. Never worked at Subway before but this seems pretty accurate :D. Nice work!
A few issues that I can say on top of my head was that it's quite hard to distinguish between the cucumber and the lettuce at a glance as they look really similar and having the same colour, making this one of the easiest causes of a failed attempt. The game also does not push the player enough to force players making rushed decisions, which I think drags down the speed of the game and makes it less exciting. Something like tightening the timer would do te trick.
Anyway, this is a very nice entry indeed! Well done!