Combine the lime juice, garlic, oil and half of the coriander in a shallow ceramic dish. Add the chicken fillets; turn to coat. Cover and chill dish for 15 minutes, or longer if time permits. Combine the tomatoes, red onion and the remaining chopped coriander in a bowl. Set aside.
Meanwhile, make the chipotle chilli yoghurt: Combine all of the yoghurt ingredients in a small bowl. Chill until ready to serve.
Preheat barbecue hotplate or a chargrill pan to medium-high heat. Spray the sweet corn and capsicums with olive oil. Grill corn, turning occasionally, for 12–15 minutes, or until charred. Transfer to a board; set aside to cool slightly. Grill capsicum for 1–2 minutes on each side until lightly charred. Transfer to a plate to cool.
Remove the chicken from the marinade. Grill the chicken over medium heat for 5–7 minutes on each side, or until just cooked through. Transfer to a plate and set aside to cool slightly.
5 Slice corn kernels from the cobs. Slice chicken. Arrange the lettuce, tomato mixture, corn, capsicums and chicken in four shallow serving bowls. Drizzle with the chipotle chilli yoghurt and sprinkle with the pepitas. Serve with coriander leaves and lime wedges.