In a serving bowl, combine 1/8 cup red wine vinegar, 1/4 cup mirin, 1/8 cup brown sugar, 3 teaspoons grated ginger, and 1/8 cup lime juice.
Stir the mixture well to blend the ingredients.
Add 1 large sliced cucumber and 1/4 cup sliced onion to the bowl.
Toss gently to coat the cucumber and onion with the mixture.
Chill the mixture for 30 minutes to blend the flavors.
Serve the Ginger-Spiced Cucumbers after chilling.