Zest the orange and then cut it in half and juice half of the orange, and place the zest and juice in a medium bowl.
Add the olive oil, rose harissa paste, honey, dried mint and half of the salt to the orange and mix it well.
Dry the skin of the salmon well.
Pour the marinade onto a shallow plate and then place the salmon fillets onto the marinade, skin side up. Carefully paint the sides of the salmon with a pastry brush, taking care not to get too much marinade onto the skin.
Transfer the salmon to the fridge and marinate for 30-60 minutes. Remove the fish from the fridge 10-15 minutes before cooking.
Heat a 28cm or 11" frying pan over a high-medium heat, then pour enough oil into it to just cover the base. The oil should be hot but not shimmering or smoking hot!Season the salmon skin with the remaining salt and place it skin side down in the oil and cook on the skin side for 4-5 minutes.
Flip the fish onto the flesh side and cook to your liking, a minimum of 60-90 seconds and a maximum of 4-5 minutes.
Remove the fish and place it on a board to rest for a minute or so.
Pour out the cooking oil from the pan into a bowl and discard it.
Scrape in any leftover marinade into the pan, then use the residual heat in the pan to gently warm the marinade to form a sauce.
Season the skin of the salmon with a pinch or two of sumac before serving.