Sumac–available at spice stores–adds a subtle piney, tangy note, but don’t worry if you can’t find it: The salad will still have loads of flavor complexity without it. You could also sub 1 teaspoon of prepared horseradish for the wasabi powder.

Ingredients

• 1 cup sugar
• 1 cup cider vinegar
• 1/2 cup water
• 1 teaspoon kosher salt
• 2 teaspoons mustard seeds
• 1 1/2 teaspoons wasabi powder
• 3 tarragon sprigs
• 1 English cucumber, thinly sliced
• 3 tablespoons extra-virgin olive oil
• 2 tablespoons sherry or white wine vinegar
• 1/2 teaspoon ground sumac (optional)
• 8 cups cubed red watermelon
• 3 ounces feta cheese, crumbled (about 3/4 cup)
• 1/2 cup chopped fresh mint
• 1/4 cup sliced pitted kalamata olives
• 1/4 cup chopped fresh dill

Preparation

1. Combine first 7 ingredients in a medium saucepan over high heat; bring to a boil.
2. Remove pan from heat; cool completely.
3. Place cucumber slices in a large bowl; pour vinegar mixture over cucumbers.
4. Cover and chill cucumber and vinegar mixture 8 hours or overnight.
5. Combine oil, vinegar, and sumac, if desired, in a small bowl, stirring well with a whisk.
6. Strain cucumbers; discard liquid and tarragon sprigs.
7. Place about 2 tablespoons cucumbers on each of 8 plates.
8. Place 1 cup watermelon cubes on each plate.
9. Top watermelon evenly with cheese, mint, olives, and dill. Drizzle evenly with vinaigrette.