Salmon Sandwich is the 3rd and final item unlocked in the Fish Marketplace. The Fish Marketplace is a Regional Commercial building that is unlocked at Level 25 and requires the Frosty Fjords region to be unlocked.
Salmon Sandwich can be produced in 564 minutes(9 hours, 24 minutes) in 3 stages without using the Global Trade HQ or a Speed-Up Token. Based on this production time, the simoleons/minute is 3.90. (High-tech Factories and 3-star shops were used for these calculations.)