irish stout lamb stew

Name: irish stout lamb stew
Ingredients: 1 leek, rinsed, sliced lengthwise then crosswise into 1/2 pieces; 1 stalk celery, diced; 1/2 medium onion, diced; 2 slices bacon, chopped; 2 pounds lamb from a leg of lamb, chunked into 1 pieces, excess fat and silver skin trimmed; 2 parsnips, peeled and cut into 1/2 pieces; 2 carrots, peeled and cut into 1/2 pieces; 4 small red skinned potatoes, quartered; 4 sprigs thyme; 2 sprigs rosemary; 1 bay leaf; 1 1/2 cups beef broth; 1 14 ounce can irish stout beer, such as Guinness; 1 teaspoon cornstarch mixed with 2 teaspoons water; 1 cup frozen peas; 1 cup frozen pearl onions; 1/4 cup chopped parsley