Irish Lamb and Turnip Stew

Name: Irish Lamb and Turnip Stew
Ingredients: 3 tablespoons extra-virgin olive oil, plus more for the roux; 3 1/2 pounds boneless lamb shoulder, cut into 2-inch pieces; Kosher salt; Pepper; 2 small yellow onions, quartered; 8 garlic cloves, crushed; 6 tablespoons all-purpose flour; 1 cup dry white wine; 4 cups chicken stock or low-sodium broth; 3 small turnips, peeled and quartered; 1/2 pound medium carrots, cut into 2-inch pieces; 8 fingerling potatoes (3/4 pound); 3 tablespoons heavy cream; Chopped parsley and mint, for garnish; Crusty bread, for serving