Wash and slice the cucumbers into rounds. If using larger cucumbers with lots of seeds, you can remove some of the center first if you want a firmer texture.
In a bowl or jar, mix together: rice vinegar, lemon juice, soy sauce, sesame oil, minced garlic, dill, onion powder, black pepper, red pepper flakes, salt. Taste and adjust the seasoning if needed.
Place the sliced cucumbers in a large bowl or container. Pour the dressing over the top and toss well so all the cucumber slices get coated.
Cover and refrigerate for at least 20 to 30 minutes so the cucumbers can soak up the flavor.
Stir again before serving and enjoy cold.
