Mashed Parsnips and Scallions - Lidia

Ingredients

• 1 pound parsnips, peeled and cut into 2-inch lengths
• 1 large Idaho potato (about 8 ounces), peeled and sliced 1 ½ inches thick
• salt
• 1 bunch scallions, including tender greens, trimmed, cleaned and sliced thin (about 1 cup)
• ½ cup milk
• 4 tablespoons unsalted butter
• 1 teaspoon grated lemon zest
• Freshly ground black pepper