Pacific Northwest Burger

Ingredients

• 1/2 cup water
• 1/4 cup rice vinegar
• 1 tablespoon sugar
• 1 teaspoon salt
• 1 1/2 cups very thinly sliced radish
• 1/3 cup canola mayonnaise
• 1 1/2 tablespoons grated fresh ginger
• 2 teaspoons rice vinegar
• 1/2 teaspoon sugar
• 1 tablespoon lower-sodium soy sauce
• 1 tablespoon Thai sweet chili sauce
• 4 (6-ounce) salmon fillets, skinned
• 1/2 teaspoon freshly ground black pepper
• 1/4 teaspoon kosher salt
• Cooking spray
• 4 (1 1/2-ounce) hamburger buns
• 1 1/2 cups watercress