Season the meat with salt and pepper and sear it in the oil, over a very high flame. Add the onion and, once it is translucent, the mole rojo and the stock and simmer, covered, over a very low heat for 1 hour or a little longer - until the meat just begins to soften. Add the carrots and potatoes (and a little more stock if the stew looks too dry), and simmer for 20 minutes more until the vegetables are done and the meat tender. Serve with rice.
