My batch is always by sight until it looks equally balanced. From memory, it's (1) purple onion, (2) peeled and seeded cucumbers, and at least (4) large tomatoes. Squeeze (2) lemons, and splash some really green olive oil in. Salt to taste, & let sit. We thinly chiffonade slice about 10 basil leaves and toss it around.
I like most cukes and onions. Its not often i try one i dont like. My vinegar selection is massive. I have a few well over 20yrs old and good aged Chinese black vinegar from central China. Most often though i just use a very affordable cider vinegar or i get Japanese rice vinegar by the gallon. This is not the seasoned stuff for sushi. Its just rice vinegar and makes great cuke salad.
This is sweet picked radish. A common side dish in Korea with fried chicken. VERY easy to make and ready in a few days. If you want to try it google "Chicken Mu or Moo". I stain mine with turmeric but that is optional.