- 1 cup olive oil
- 2 tablespoons fresh lime juice
- 2 tablespoons Champagne vinegar
- 1/4 cup finely chopped shallot (1 large)
- 1 (2-inch) fresh serrano chile, thinly sliced crosswise (1 tablespoon)
- 1 tablespoon chopped fresh thyme
- 1/2 teaspoon salt
- 1 (6-lb) piece seedless watermelon
- 1 cup rice vinegar (not seasoned)
- 2 tablespoons sugar
- 1/2 lb arugula (6 cups)
- 1/2 lb feta, crumbled (2 cups)
- 1 (2-inch) fresh serrano chile, thinly sliced crosswise (1 tablespoon)
- Whisk together all vinaigrette ingredients and chill in an airtight container at least 8 hours to allow flavors to develop. Shake or whisk before using.
- Remove and discard outer green skin from watermelon with a sharp knife. Using a vegetable peeler, shave enough 2-inch-long pieces from white rind to measure 1/2 cup. Transfer to a heatproof bowl. Reserve remaining watermelon.
- Stir together rice vinegar and sugar in a 1-quart heavy saucepan and bring to a boil. Carefully pour boiling-hot vinegar mixture over white rind shavings and let stand at least 1 hour.
- Trim and discard remaining white rind from watermelon, then cut watermelon into 18 pieces (about 3-inch squares).
- Toss arugula with just enough vinaigrette to coat and salt to taste.
- Divide arugula among 6 plates, then place 1 watermelon piece in center of each plate. Top each with a scant 1/4 cup feta, then top with another watermelon piece and more feta. Top each with a final watermelon piece for a stack of 3 on each plate.
- Remove pickled rind from vinegar with a slotted spoon and drain on paper towels. Top watermelon stacks with pickled rind and chile slices, then drizzle remaining vinaigrette around salads.