Place the chicken fillets onto a plate and season well with salt. Pour over the lemon juice and toss to coat.
Combine breadcrumbs, flour and smoked paprika in a shallow wide plate or dish. Working with one chicken fillet at a time, press into the breadcrumb mixture to coat well on each side. Transfer to a plate and set aside.
Heat a large non-stick frying pan and spray generously with oil. Cook the burger buns, cut side down, in batches, adding more oil when necessary until golden brown and they have a nice seal on them. (you want a nice seal to stop the burgers going soggy). Transfer buns, cut side up to a clean chopping board or work surface. Spread each bun base with mayonnaise and top with lettuce and cheese. Set aside.
Heat the same pan again over medium high heat and drizzle with 1 tablespoon oil. Cook chicken, in batches, for 2-3 min each side or until golden brown and cooked through. Brush with tops with Peri Peri Sauce then transfer 2 fillets to each burger bun on top of the cheese and spoon on a little more mayonnaise.
Spoon the tops of each burger bun generously with Peri Peri Sauce and spread to the edges. Place tops onto burgers to complete. Serve immediately with oven baked or air-fried chips or fries. If desired, serve extra mayonnaise with some Peri Peri Sauce swirled through for a yummy dipping sauce. Serve with lots of paper towels. They can be a bit messy!