Roasted Salmon With Whipped Feta and Peas

Ingredients

• 1 large lemon
• Four (6-ounce) center-cut salmon fillets (skin-on or skinless)
• 3 tablespoons plus 2 teaspoons olive oil, divided
• 1/4 teaspoon plus 1/8 teaspoon fine salt, divided
• 1/4 teaspoon freshly ground black pepper
• 4 ounces feta cheese
• 1 cup fresh peas (or defrosted frozen peas)
• 1/4 cup fresh flat-leaf parsley leaves (or dill or mint)
• 3 tablespoons plain Greek yogurt
• 1 small garlic clove
• 3 cups (3 ounces) packed watercress leaves and tender stems (or baby arugula)