Preheat oven 200°C fan forced. Scrub the sweet potatoes under water with a clean brush. Pat dry. Pierce them all over, at least 8 times with a fork. Rub the skins all over with a little olive oil. Season well with salt and freshly ground black pepper.
Roast in a pan for 40-55 minutes or until tender through to the centre.
Meanwhile, sprinkle seasoning over both sides of the chicken . Heat a frying pan over medium heat. Add remaining oil and chicken. Cook 5-6 minutes each side or until cooked through. Set pan aside for 10 minutes then shred the chicken. Tossing the shredded chicken in the warm pan juices.
Smash the avocado then stir in 1 tablespoon each of chives, parsley and coriander. Season. In a seperate bowl stir chilli through the mayonnaise.
Split the sweet potatoes down the centre with a sharp knife and ease open. Spoon in chicken and avocado. Drizzle with mayonnaise and serve with remaining herbs and lime.