To make croutons, spread bread over a baking tray. Drizzle with oil. Toss to coat. Bake in 200 °C oven (fan-forced) for 8-10 minutes or until crisp and golden. Remove. Cool.
Meanwhile, to make dressing, whisk all ingredients in a small bowl with a fork until combined. Cover and refrigerate.
Heat oil in a medium non-stick frying pan over a medium-high heat. Add chicken and season with pepper. Cook about 5 minutes on each side or until cooked through. Remove and cool. Thinly slice.
Cut corn kernels from cobs. Place in a large bowl. Add lettuce, cucumber, tomatoes, avocado, onion and croutons. Gently toss to combine.
Divide salad over 4 plates. Top with chicken. Drizzle with dressing.