Heat a small frying pan over a high heat. When the pan is hot, add the olive oil. Season the salmon with salt and pepper and place it, skin-side down, in the pan. Cook for 4 minutes, then turn the fish over and cook for a further 2 minutes.
Heat another small frying pan on the hob. Cut the orange in half and place the orange halves, cut-side down, in the pan. Sear the orange halves until they start to blacken. Remove the oranges from the pan and squeeze the juice into the frying pan. Bring the juice to the boil and reduce it until you have around 1 tablespoon left. Whisk in the extra virgin olive oil and season with salt and pepper.
Place the avocados in a mixing bowl, add the remaining ingredients and season with salt and pepper.
Spoon the avocado salad into the centre of each plate. Place a piece of salmon on top and drizzle with the burnt orange vinaigrette.