1 tablespoon olive oil
1 pound boneless leg of lamb, trimmed of all fat, cut into 1/2-inch dice
1 1/4 pounds leeks (see NOTE)
Salt
1 1/2 teaspoons ground cumin, or to taste
Freshly ground black pepper
4 cups low-sodium or homemade chicken broth
2 cups water
1/4 cup pearl barley (see headnote)
1/2 pound all-purpose potatoes, peeled and cut into 1/4-inch dice
1 large parsnip, peeled and woody core removed, the remaining flesh cut into 1/4-inch dice
1 or 2 tablespoons chopped fresh parsley (optional)