Place the strips of chicken in a bowl with the buttermilk and mix together well. Set aside for at least an hour but preferably overnight.
Meanwhile, make the pancakes: Place the flour in a large bowl and make a well in the middle. Beat together the egg and egg yolk with the milk and slowly add to the flour mixing well with a small whisk or wooden spoon until you have a smooth batter. Stir in half of the chopped chives. Set aside for about 30 minutes.
When ready to make the pancakes, rub a 20cm frying pan with a little sunflower oil and heat over a medium heat. Add a small ladleful of batter, just enough to coat the base of the pan, then swirl around the pan quickly until it covers the base. Cook for a minute until lightly coloured underneath then using a palette knife, flip over and cook for a further minute. Tip out onto a plate and place the pan back on the hob and continue to make 9 more pancakes adding more sunflower oil if needed.
Heat a tablespoon of the sunflower oil in a large wok or frying pan. Remove the chicken from the marinade and add to the pan stirring quickly until beginning to turn a golden colour. Add the peppers and sweetcorn and cook for a further 5 minutes then add the spring onions. Remove from the heat.
Preheat the oven to 200°C /180°C /Gas 6. Lay a pancake out on a board and place a few spoonfuls of the filling in the middle. Wrap to make a parcel and place in a shallow baking dish. Repeat with the remaining pancakes. Sprinkle the remaining cheese on top and bake for 15 minutes.
Cut the avocado in half and remove the stone. Spoon the flesh into a bowl and add the lemon juice. Mash together well until coarsely mixed. Serve the parcels with a dollop of guacamole and a tablespoon of soured cream.