Watercress Salad with Papaya and Lemon Dressing

Name: Watercress Salad with Papaya and Lemon Dressing
Ingredients: 1 fresh lemon; 1 papaya, peeled, sliced, and seeds removed and reserved; 1 teaspoon Dijon mustard; 1/4 cup rice wine vinegar; 1 teaspoon salt; 1/4 teaspoon freshly ground black pepper; 1 cup extra-virgin olive oil; 6 cups mixed fresh watercress and greens, soaked in salt water to remove grit, rinsed and dried in a salad spinner; 2 English cucumbers, peeled, quartered lengthwise, seeds removed and sliced into 1/4-inch thick slices; 1 pint cherry tomatoes, halved; 1 papaya, peeled, shredded into strings and cut into bite-sized lengths