Thinly slice the cucumbers and onion. You can use a mandoline for even slices. Place the sliced cucumbers and onions in a large mixing bowl.
Chop the fresh dill and add it to the bowl with the cucumbers and onions.
In a small bowl, whisk together the vinegar, olive oil, and maple syrup. Season the dressing with salt.
Pour the dressing over the cucumber, onion, and dill mixture. Toss everything together until the vegetables are well coated with the dressing.
Let the salad sit for at least 15-20 minutes to allow the flavors to meld together. For best results, you can refrigerate it for a few hours before serving.
Serve the salad chilled. It's a refreshing side dish that's perfect for summer! Enjoy your vegan cucumber onion dill salad!