Step 1

Pickle the radishes: Combine the red radishes, shallot, vinegar, and salt in a medium bowl and mix well to combine. Cover the bowl and set aside at room temperature for 2 hours to pickle, or transfer to an airtight container and place in the refrigerator for up to 3 days. Be sure the radish and shallots are fully submerged in the pickling liquid so they can all turn pink—the liquid increases as it sits so you can periodically press the mixture into the liquid.

Step 2

Make the dressing: Place the olive oil, balsamic vinegar, red wine vinegar, and salt in a medium jar, tightly screw on a lid, and shake well to combine. When you are ready to assemble the salad, stir in the pomegranate seeds and reshake the dressing.

Step 3

Make the salad: Heat the oven to 300°F.

Step 4

Line a sheet pan with parchment paper, add the walnuts, and spread out evenly. Toast for 6 to 8 minutes, or until fragrant, then remove from the oven and set aside to cool. Coarsely crush the nuts directly on the sheet pan using the back of a wooden spoon and set aside.

Step 5

Remove the radicchio leaves from the head all the way to the center, then discard the core (cut it in quarters if needed to remove the tighter inner leaves). Tear the leaves into bite-size pieces and place in a large mixing bowl. Add the endive leaves and crushed nuts. Drain the pickled radishes and shallots (discard the pickling liquid or save it to season sauces or stews) and sprinkle over the salad. Add the shaved watermelon radishes, then shave the apple (or slice as thin as possible) and add to the salad. Drizzle with the dressing and gently toss. Transfer to a serving bowl and serve immediately.