Put your thinly sliced onion in a small bowl and add about 3 Tablespoons red wine vinegar.  I sometimes add a pinch of sugar, especially if your onion isn’t a red onion.  Let sit at room temperature for 20 minutes or so.  Slice the rind off of your melon and cut the whole thing into bite sized chunks.  Slice your cucumbers on the diagonal.  Put both the melon and cucumbers in a large serving bowl, sprinkle with a small amount of salt, and mix gently.  Drizzle a bit more red wine vinegar over the melons and cucumbers.  Sprinkle with the herbs, a bit of olive oil, and some freshly ground black pepper.  Top with the shaved cheese and pickled onions.