Put the cucumbers and tomatoes in separate bowls and pop them in the fridge just until they're cold, about 30 minutes.
Meanwhile, add the onions to a small bowl. Add the vinegar, 2 tablespoons of the oil, and a healthy pinch of salt, and mix well with your hands. Let the onions sit just until they get pickly, a few minutes.
In a separate small bowl, stir together the remaining 2 tablespoons of oil, the lemon juice, and a good pinch of salt until the mixture looks creamy. Combine the tomatoes and cucumber in one bowl, pour in the lemon dressing, and toss gently but well.
Grab a large platter (or 4 to 6 plates) and make a pretty layer of cucumbers and tomatoes, so the colors and types of the vegetables are well divvied up. Give the onions one more toss, then use your hands to add them (reserving their pickly liquid) here and there over the cucumbers and tomatoes. Scatter on the olives and mint. Use your hands to crumble the feta into pieces large, medium, and small as you scatter it on top. Finally, drizzle on the liquid remaining in the onion bowl. Eat straightaway.
Photo by David Loftus
From A Girl and Her Greens by April Bloomfield with JJ Goode. Copyright 2015 April Bloomfield. Excerpted by permission of Ecco, an imprint of HarperCollins Publishers.