Cut the tomatoes into quarters. Cut the cucumber in half lengthwise, then slice it into thick slices. Finely slice the half onion and shred the basil.
Add the salad ingredients to a large bowl and mix well. Check the bottom of the bowl. If the tomatoes release too much water, you might want to drain off a bit of the liquid before adding the dressing (too much water will wash down the flavor).
Add the dressing ingredients to a jar with a tightly fitted lid. Shake vigorously until emulsified. Alternatively, whisk together the dressing ingredients into a small bowl.
Pour the dressing over the salad and mix very well to coat. Taste and adjust the seasoning, adding more fine salt if necessary. Then sprinkle with extra fresh basil and enjoy!
