Rinse meat and pat dry. Rub vigorously with the spice mixture all around and place on a baking tray. Roast in the preheated oven (electric cooker: 120 °C/circulating air: 100 °C/gas: see manufacturer) for approx. 3 3⁄4 hours.
Take the roast out of the oven and let it rest for about 5 minutes. Cut the roast open. Serve with salsa and the tortilla.