Bring the stock and 2 cups water
to the boil in a large saucepan, then reduce the heat to a simmer.
Add the chicken and cook for 10
minutes, or until tender.
Remove from the heat, cover and
set aside until cool.
Strain, reserving the stock, shred
the chicken.
Place the avocado, cumin, garlic,
coriander, 1 tbsp of the lime juice, 2 tsp of the sweet chili sauce
and 1 tbsp of the sour cream in a bowl and mash with a fork.
Season, then set aside.
Combine the onion, tomato and
remaining lime juice in a bowl and season.
Brush both sides of the tortillas
with a little oil.
Heat a frying pan over high heat,
then cook the tortillas, one at a time, pressing down with an egg
flip on each side for 30 seconds, or until golden. Keep warm.
Place a tortilla on each plate and
top with one quarter each of the lettuce, chicken, cheese, tomato
mixture, avocado and the remaining sour cream.