1/2 cup soy sauce
1/4 cup mirin
1/4 cup rice vinegar (not sushi vinegar)
1/4 cup sugar
1/2 tsp. ground ginger
1/4 tsp. red pepper flakes

  • mix all ingredients and simmer for 2-3 minutes

source: comment on https://cooking.nytimes.com/recipes/1012984-chicken-teriyaki