Slice the cucumbers thinly using a sharp knife, aiming for consistent, delicate rounds that show off their crisp, juicy interior.
In a small saucepan, combine rice vinegar, salt, sugar, and crushed garlic, then bring to a gentle simmer over medium heat, stirring until the salt and sugar dissolve completely. Once bubbling, remove from heat and let cool slightly.
Place the sliced cucumbers in a mixing bowl, then pour the warm vinegar mixture over them, ensuring all slices are coated evenly. Toss gently to distribute the flavors and herbs.
Add chopped dill and a pinch of red pepper flakes to the bowl, then toss again to incorporate the herbs and spice.
Cover the bowl with plastic wrap or a lid and let the salad marinate in the refrigerator for at least 15 minutes, allowing the cucumbers to soften slightly and absorb the tangy flavors.
Give the salad a quick toss before serving to refresh the flavors, then transfer to a serving dish. The cucumbers should be crisp yet tender, glistening with the flavorful marinade.