Preheat the barbecue grill and flatplate to high (see Make it yours). Thinly slice the onion and cucumber. Thinly slice the cabbage with a sharp knife or mandoline. Cut the bread rolls in half. Put the chicken flat on a board, put your hand on top and halve horizontally into fillets.
Step 2 — Pickle cucumber
Combine 1 tbs white vinegar and 1 tsp sugar in a bowl. Add the cucumber and toss to combine. Set aside to pickle, tossing occasionally, until needed. Combine the barbecue seasoning and 1 tbs olive oil in a large bowl and season with salt and pepper. Add the chicken and turn to coat.
Step 3 — Cook onion and chicken
Heat 2 tsp olive oil on the barbecue flatplate. Add the onion and cook, tossing occasionally, for 4-5 mins until charred. Remove from the flatplate. Meanwhile, cook the chicken on the barbecue grill for 3-5 mins each side until browned and cooked through. Remove from the grill.
Step 4 — Toast rolls
Put the rolls, cut-side down, on the barbecue grill and cook for 4-6 mins until toasted. Remove from the grill.
Step 5 — Serve up
Combine the cabbage and 1½ tbs mayonnaise in a large bowl and season with salt and pepper. Halve the chicken widthwise. Layer the roll bases with half the slaw, the drained pickled cucumber, chicken and onion, then sandwich with the roll tops. Serve with the remaining slaw and enjoy!
Step 6 — Make it yours
Don't have a barbie? No worries, you can use a chargrill pan or frypan – just adjust the cook times!