1) Preheat the oven to 200 degrees C.
2) In a small bowl, mix together the mustard, chilli powder, cumin, allspice, oregano, brown granulated sugar, and garlic. Place the pork in a 20 by 30 cm roasting pan. Spread the mustard mixture over the top and sides of the pork to form a crust. Add the onions, carrots, and chicken stock to the pan. Roast for 1 hour and 15 minutes or until a meat thermometer inserted into the thickest part of the pork registers 70 degrees C. Allow the pork to rest for 10 minutes before serving. Remove the vegetables and arrange on a serving platter. Season the pan juices with salt and pepper and pour into a small serving pitcher.
3) To serve, slice the pork into 1/2 cm slices. Arrange the pork slices on the serving platter with the roasted vegetables and serve with the pan juices.
Cook's Note: This recipe will also work using a 1 kg beef roast. Allow an extra 10 to 15 minutes of cooking time.