Macerate the Tomatoes: Place the chopped heirloom tomatoes in a large colander set over a mixing bowl. Sprinkle with the kosher salt and let them sit for 10 minutes. This draws out the excess water and creates a flavorful juice base.
Build the Vinaigrette: Take the bowl containing the extracted tomato juices. Add the lemon juice, apple cider vinegar, raw honey, and Dijon mustard. Whisk vigorously.
Stream the Oil: While continuously whisking, slowly drizzle the extra virgin olive oil into the acid mixture. Whisk until the dressing is completely opaque and emulsified.
Combine the Base Vegetables: In your final serving bowl, combine the drained tomatoes, diced cucumber, fresh corn kernels, and thinly sliced red onion.
Dress and Rest: Pour the emulsified vinaigrette over the vegetables. Toss gently with large spoons. Let the mixture sit at room temperature for 5 minutes.
Garnish and Serve: Just before serving, gently fold in the torn basil leaves and crumbled feta cheese so they don't bruise.
