Instead of vinegar, the dressing for this salad leans on lime juice for freshness and olive brine to enhance the flavor of the olives. Since black radishes can sometimes be a little tough, slice them as thinly as possible; use a mandoline to make this task easier. Watermelon radishes tend to be sweeter and can be cut a little thicker for heartier crunch. If you can't find these types of radishes, use classic red radishes instead.
1/3 cup kalamata olives, finely chopped
1/4 cup extra-virgin olive oil
2 tablespoons fresh lime juice
2 tablespoons kalamata olive brine
2 medium watermelon radishes (about 4 oz.), thinly sliced