The key to this sanger is CSLP - Critical Sandwich Layering Protocol. I like to use New Zealand hoki, also known as blue grenadier. Sustainable choices are good so you can enjoy fish sandwiches for years to come.
For the tartare sauce
60g dill pickles
40g capers, rinsed
½ tsp dijon mustard
zest of half a lemon
small handful each of parsley and dill
½ tsp pepper
500ml mayonnaise, either homemade or good quality store-bought
For the potato crisps
2 large desiree potatoes
oil for frying
For the sandwiches
6 x 120g pieces of your favourite white fish
salt and white pepper to taste
flour for dusting
2 cups panko breadcrumbs
oil for frying
6 slices burger cheese (such as Hi-Melt Burger Slices)
6 super fresh soft buns or baps
2 tbsp good butter
1 small white onion, finely diced and placed in iced water for 5 minutes
1 cup iceberg lettuce, shredded
1 lemon, sliced into small chunks
Place the pickles, capers, mustard, lemon zest, herbs and pepper into a food processor. Process by pulsing and scraping the ingredients back down so you have nicely chopped mix, not a paste. Transfer into a large bowl with the mayonnaise and mix well. (Note: This will make more than you need for the sandwiches. Keep it in the fridge.)
Thinly slice potatoes on a mandolin and wash well. Drain on paper towel and pat dry.
Heat cooking oil to 160C and add the potatoes. Fry until crisp and lightly golden. Drain on paper towel and season.
Season fish with salt and white pepper and dust in flour.
Whisk eggs, loosening the mix with a splash of water.
Pass fish through the eggs and coat in breadcrumbs. Allow crumbed fish to set in the fridge for 30 minutes.
Heat cooking oil to 180C and fry fish for 3 to 4 minutes depending on thickness. Be mindful the fish will continue to cook when you remove it from the oil. Season to taste and top with cheese slices. Allow to rest for one minute.
Slice buns in half and spread the cut surfaces with butter. Toast buns two at a time, cut-side down on a flat-top barbecue or frypan. (You want the bun tops to stay soft so don't be tempted to put them in the oven.) Place each of your bun bottoms on a plate.
This next bit is important. It is known as CSLP – Critical Sandwich Layering Protocol. It relates to flavour, texture and ethereal joy, so listen: Spread a layer of tartare sauce on the bun bottoms. Also spread the bun tops with tartare at the same time and set aside.
Evenly divide and layer onion between bun bottoms. Place your crumbed, cheese-coated fish pieces on the onions. Now place a neat pile of shredded lettuce on the fish.
Place your bun tops on the lettuce and skewer a lemon chunk through the sandwich to hold it in place. Serve with fried potato crisps.