Combine all cranberry sauce ingredients in Saucy (or another saucepan) over medium heat.
Bring to a boil, then reduce heat and simmer for 10–15 minutes uncovered. Set aside to cool.
Smear a heaping spoonful of cranberry sauce on bottom half of the onion roll, then top with turkey slices and muenster. Place under broiler just until cheese has melted.
Spread sansho mayo on the top half of roll and serve.