Asparagus, Green Pea, and Scallion Sauce - Lidia

Ingredients

• 1 to 1-1/2 pounds asparagus spears, preferably 1/2-inch wide or less
• 6 tablespoons extra-virgin olive oil
• 1 medium onion finely chopped (about 1 cup)
• 1 large leek, both green and white part sliced into 1/2-inch pieces (about 1 cup)
• 1 teaspoon salt
• ¼ to 1/2 teaspoon dried peperoncino (hot red pepper flakes), or to taste
• 10 ounces frozen peas, thawed or 1 pound fresh peas, shelled
• 2 cups finely chopped scallion
• 2 tablespoons butter, cut up
• 1/3 cup water plus more if needed
• 1/2 teaspoon shredded fresh mint leaves