Leave on the corn husks on; trim the bottom off of each ear (to ease husk removal) and immerse in a pot of boiling water for 10-12 minutes, or until it smells corny. Remove from water and let cool. (You can do this step the night or day before you make this salad. )
Husk each ear. Shave the kernels off of each cob and place them in a medium-sized mixing bowl.
Wash the celery well. Trim the ends and any loose threads from the stalk. Slice diagonally, alternating directions. Pieces should be about an inch wide. Add to the bowl of corn.
Remove the tops and scrape the tough outer skin of the purple daikon. Wash well. Slice in half lengthwise; rest each half on the flat surface and cut thin half-moon shapes; then halve each half-moon. Add to the salad bowl.
Wash the tomatoes well. Halve them lengthwise; cut each half into thirds and add to the salad.
Cut a small red spring onion in half, lengthwise. Cut one half into half-moons and then chop each half-moon into small pieces; add to the mix.
Add chopped cilantro if using.
Squeeze the lemon and mix with the olive oil. Drizzle over the salad. Add sea salt to taste, and mix well. Serve.