- STEP 1
Heat grill to high. Put the chicken breasts between 2 pieces of cling film and bash with a rolling pin until they’re about half their original thickness. Whizz the toast in a food processor to rough breadcrumbs, then tip out onto a plate.
- STEP 2
Beat the egg and mustard together in a bowl and season. Dip the chicken into the egg, let the excess drip back into the bowl, then press into the toasty breadcrumbs. Put under the grill on a flat baking sheet and grill for about 10 mins, turning once, until golden and crisp on both sides and the chicken is cooked through.
- STEP 3
Beat the lemon zest, juice and lots of black pepper into the mayonnaise. Spread some of the mayo onto the bottom halves of the buns, top with a chicken breast and salad of your choice and serve.