Trim off any fat off the chicken.
Wash, drain and pat dry chicken.
In a microwave safe glass plate or casserole, cook chicken on high power for 2 minutes. Flip them and cook for additional 3 minutes. Remove from microwave and keep them aside.
In another microwave safe plate, roast red chilies till crisp, about a minute. Remove and them aside.
In the same plate, roast onions along with their peels for 2 minutes. Remove from microwave and separate onions from the peels.
In a small bowl, heat oil for 30 seconds. Add garlic and cook for 1 minute.
In a deep bowl, heat the stock for 5 minutes till it's boiling.
Add ginger, lemongrass, lime juice, fish sauce, coriander stalks, basil, and chicken.
Add onions and garlic reserving some for garnish.
Place the bowl back in the microwave and heat for 2 minutes.
Remove the soup to serving bowls. Sprinkle crushed red chilies, onions and garlic over the soup.