For dressing, I made a mixture of soy sauce, lemon juice, mirin, and sesame oil (to your liking, I did not measure) and dressed the onion. I spread the oinon on the plate and layered sliced tomato (skinned). I sprinkled some Kosher salt, good fruity olive oil and freshly ground peper (I used white pepper) on the tomato slices and garnished it with chopped chives. I chilled it in the refrigerator before serving.
It is very nice refreshing salad in hot weather. It may have lost some of the health benefits but the taste is very mild and even those who may not like raw onion will be able to enjoy it.