The best replacement for mirin is sake.

The best alternatives to mirin are rated as following:
★★★★★  sake
★★★  rice wine vinegar
★★★  rice wine
★★★  rice vinegar
★★  aji mirin
★  chinese rice wine
★  cooking sake
★  shaoxing
★  cooking wine
★  chinese cooking wine
★  sushi vinegar
★  mirin seasoning
★  mirin
  saki
  dashi
  dry sherry
  shaoxing wine

Your alternative for mirin is not listed? Suggest!
Speaking about mirin, one probably shouldn't forget about soy sauce.

Other search terms related to mirin and their ratings are:
★★★★★ soy sauce
You have in mind a companion for mirin and it is not yet here? Propose!



Google Trends

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mirin
sake
rice wine vinegar