1/2 cup rice vinegar
2 tablespoons sugar
2 tablespoons fresh lime juice
2 tablespoons minced fresh ginger
1 hot red chili, minced (1 1/2 tablespoons) [or 1/4 teaspoon red pepper flakes]
1 tablespoon toasted sesame oil
3 cucumbers, peeled, seeded, and cut crosswise into 1/4-inch slices
4 scallions, white and light green parts, sliced thin
1/4 cup packed fresh basil leaves, chopped
Table salt and ground black pepper
1. Bring vinegar and sugar (and red pepper flakes, if using) to boil in saucepan over medium-high heat. Reduce heat to medium-low and simmer until mixture reduces by half, 5 to 6 minutes. Transfer to medium bowl and cool to room temperature.
2. Whisk in lime juice, ginger, chile, and sesame oil. Toss in cucumbers, scallions, and basil; season with salt and pepper, and let sit for 10 minutes or up to 1 hour. Serve.