Step by step
Cover the chicken breasts with a sheet of cling film and bash the thickest part with a rolling pin. Ideally the breast will be a similar thickness all over so it cooks evenly. Mix together 1 tbsp of the Piri-piri seasoning mix, the juice of half the lime, the oil and the finely chopped spring onions to make a marinade. Pour this over the chicken and leave to marinate overnight or for as long as possible.
The chicken can be cooked on the BBQ, in a griddle pan or grilled. Whichever way you do it, cook on a medium heat for 10-15 minutes, turning regularly. It should be charred on the outside and juicy but cooked in the middle.
While the chicken is cooking, mix together the remaining Piri-piri seasoning and the mayonnaise. Slice the avocado and dress with lime juice and a good pinch of salt. Tear the Little Gem leaves and toast the buns.
Lay the Little Gem leaves on the bottom half of each bun, lay the cooked chicken breast on top, add a dollop of Piri-piri mayonnaise and top with the spring onion strips, slices of avocado before topping with the bun lid.
Note: You can buy spicy or mild Piri-piri seasoning blends, choose whichever suits your taste.