Prick the potatoes all over and cook for 10 minutes in a microwave on full power. Remove from the microwave, cut each in half and scoop out most of the potato, leaving a 1 cm (1/2 inch) border of potato next to the skin. Discard the potato (or keep for mashed potato for another recipe).
Cut each half into 2 wedges and place on a baking sheet. Mix the oil with the Cajun spice and brush over the potato skins on both sides. Place on a baking sheet and cook under a preheated grill for 5–7 minutes, then turn the skins over and cook for a further 5–7 minutes until crisp and golden.
Meanwhile, mash the avocado with the lemon rind and juice, season with pepper and mix in the chilli sauce and coriander. Transfer to a small serving bowl and put it on a serving platter. Place the hot potato skins on the platter and use them to dip into the guacamole.