Preheat oven to 220°C or 210°C fan bake. Line an oven tray with baking paper.
Make wedges
Slice the unpeeled 800 g potatoes into 1cm thick wedges. Place the wedges on the prepared oven tray, drizzle with 1 tbsp olive oil and season with salt and pepper and toss to coat. Arrange in an even layer and cook for 22-25 minutes, or until golden and tender. Remove from the oven and add 2 tbsp apple cider vinegar and a generous pinch of salt. Toss to coat.
Prep fish
Lay 500 g fish fillets on a board, and pat dry with a paper towel, remove any bones or scales. Add ¼ cup cornflour to a shallow bowl or plate. Whisk 2 eggs in a separate shallow bowl and add 1 cup panko breadcrumbs to a separate plate. Coat the fish in the cornflour, then dip into the egg to coat and then press into the breadcrumbs firmly to coat.
Make salad
Cut 1 lemon into wedges. Thinly slice 1 apple. Roughly chop 1 cucumber. In a large bowl combine apple, cucumber, 1 cup mixed green salad, a squeeze of lemon juice and 1 tbsp olive oil. Season with salt and pepper and toss to combine.
Cook fish
When the wedges have 10 minutes of cooking time remaining, heat 1 tbsp olive oil in a large frypan on medium-high heat. Cook the fish for 4-5 minutes on each side (depending on thickness), or until golden and cooked through. Transfer to a paper towel-lined plate to drain.
To serve
Divide the crispy fish, salt & vinegar wedges and cucumber salad between plates. Serve with tartare sauce and remaining lemon wedges on the side.