Mashed Plantains With Leeks and Fresh Herbs

Name: Mashed Plantains With Leeks and Fresh Herbs
Ingredients: 7 cups water; 1 cup low sodium chicken broth; 2 large unpeeled semi-ripe plantains, ends trimmed, each cut cross-wise into thirds (yellow with black); 1⁄2 tablespoon unsalted butter; 1 tablespoon extra virgin olive oil; 1⁄2 large leek, finely chopped (white and pale green parts only); 4 teaspoons fresh thyme, minced; 2 teaspoons fresh Italian parsley, minced; 1⁄4 cup sour cream; 1 tablespoon ground cumin; 1 tablespoon chopped pecans; 1 tablespoon butter (optional)