My assistant, Andrea Slonecker, developed this recipe for a springtime feature article in Mix, the magazine of the Oregonian. The salad is a beautiful mosaic of complementary textures and fresh spring flavors. Look for magenta-centered watermelon radishes at farmers’ markets. If you can’t track them down, substitute another radish variety. Castelvetranos are big, buttery, bright green olives that are found at most specialty markets. White balsamic vinegar adds sweet acidity without the dark color of regular balsamic, allowing the vibrant colors of this dish to shine.