In a small bowl, mix together the chipotle paste, lime juice, sugar and salt. Use to coat the pork, then leave to marinate in the fridge for 20-30 minutes. Meanwhile, segment the orange: top and tail the fruit, then cut away the skin and pith.
Cut between the membrane to release the segments, then slice each segment into 3 pieces and put in a bowl. Squeeze out any juice from the membrane into the bowl.
Preheat the grill to high. Put the marinated pork steaks on a foil-lined baking tray and grill for 6-7 minutes on each side or until completely cooked through. Meanwhile, add the avocados, onion, chilli and coriander to the bowl with the orange. Season with salt and stir to combine.
Rest the meat for 5 minutes, then cut into thin slices. Heat the tortillas according to pack instructions and serve with the pork, salsa and extra coriander.