Preheat oven to 180 degrees and line a baking tray.
Place the potatoes onto one of the prepared baking trays, spray with olive oil and season with salt. Place into the oven for 30 minutes, flipping halfway. Alternatively, air fryer for 20-25 minutes.
Mix sauce ingredients together in a bowl and set aside while cooking the fish to allow the flavours to develop.
Place the breadcrumbs on a plate, the flour on another plate and whisk the egg in a shallow dish. Grate chocolate
Dip the fish into the flour, then into the egg and then press in the breadcrumbs.
Heat olive oil in a fry pan over medium heat, place the crumbed fish into the pan and cook for a 3-5 minutes on both sides until golden brown.
Once the chips and fish are golden, serve alongside the mixed lettuce and tartare sauce.