Slow Cooker Turkey Stew with Mustard and Root Vegetables

Name: Slow Cooker Turkey Stew with Mustard and Root Vegetables
Ingredients: 4 turkey thighs , skin on, bone-in; Salt; 4 tablespoons extra virgin olive oil; 1 large yellow or white onion , roughly chopped; 1 to 2 large parsnips , peeled, cut into 1-inch pieces; 2 to 3 large carrots , peeled, cut into 1-inch pieces; 3 cups chicken or turkey stock; 2 tablespoons brown sugar; 1/3 cup yellow mustard; 1 heaping tablespoon dry mustard powder; 2 teaspoons chipotle or chili powder; 4 to 6 Yukon Gold or other yellow potatoes, peeled, cut into 1-inch pieces; 1 cup (packed) mustard greens , arugula, spinach, or parsley, roughly chopped; 1/4 cup whole-grain mustard