Discard the husk and silks from the corn cob. Crush or finely chop the garlic. Shred the cabbage. Thinly slice the spring onion. Finely chop the parsley leaves, discarding the stems.
Step 2 — Grill corn
Heat a chargrill pan over high heat until hot. Drizzle the corn cob with 2 tsp olive oil and season with salt and pepper. Cook the corn cob, turning occasionally, for 6-8 mins until charred. Remove from the pan, reserving the pan.
Step 3 — Prep chicken
Meanwhile, combine the garlic, barbecue seasoning and 2 tsp olive oil in a shallow dish. Put the chicken flat on a board, put your hand on top and halve horizontally into fillets. Add the chicken to the seasoned oil and turn to coat.
Step 4 — Cook chicken
Heat the reserved pan over high heat until hot. Cook the chicken for 2-4 mins each side until golden and cooked through. Remove from the pan and rest for 3 mins.
Step 5 — Make dressing
While the chicken is cooking, put the horseradish dressing, 2 tsp red wine vinegar and 1 tsp extra virgin olive oil in a large bowl. Season with salt and pepper and whisk to combine.
Step 6 — Get ready to serve
Slice the corn kernels from the corn cob. Add the corn, cabbage, spring onion and parsley to the dressing and toss to combine. Taste, then season with salt and pepper. Divide the slaw and chicken among plates to serve.