• 1 1/2 cups chopped seedless watermelon , plus 6 three-inch squares
• 1 spring onion or large scallion , thinly sliced, whites and greens separated
• 1/4 cup extra-virgin olive oil
• 1/4 cup cider vinegar
• 1/4 tsp. salt
• 1/8 tsp. freshly ground pepper
• 3 ounces baby arugula leaves
• 1/2 cup toasted slivered almonds

To make dressing: In a blender or food processor, puree 1 1/2 cups watermelon until smooth. Strain through sieve to make 1 cup juice. In a small saucepan, sauté onion whites with 1 teaspoon olive oil over medium heat, until soft. Add juice and vinegar; bring to a boil over medium-high flame. Lower flame and simmer until reduced to about 3 tablespoons, stirring occasionally, 20 to 25 minutes. Pour into a small bowl; cool. Whisk in remaining oil, salt, and pepper.

To make salad: Arrange watermelon squares on chilled salad plates. In a large bowl, combine arugula, almonds and sliced onion greens. Add 2 tablespoons dressing and toss gently. Top watermelon squares with salad. Drizzle with remaining dressing.