Prepare your veggies: Slice your cucumber (peeled or unpeeled) into slices, then half each slice. Quarter the cherry tomatoes, and thinly slice the red onion. Pour into a medium to large size bowl.
Using a container with a lid, combine the oil, vinegar, dijon mustard, Italian seasoning, and a pinch of salt. Shake until nice and smooth. Pour on top of the cucumber/tomato mixture.
Season with additional sea salt and top with fresh basil to serve.