Heat oil in a skillet. Add sliced onion, minced ginger, and garlic. Saute for a minute until it is aromatic.
Add red curry paste and minced coriander root. Saute for 2-3 minutes until oil starts oozing out on the side, and the mixture is aromatic.
Add coconut milk, stock, lemon zest, brown sugar, fish sauce, and lemongrass stalk. Mix well and let everything come to a boil. Simmer and let it cook for 2-3 minutes.
Add chicken and let it simmer for 7-8 minutes.
Add the veggies when the chicken is almost cooked/ and the sauce has reduced almost by half (or to the consistency you are looking for).
Cook for another 2 minutes, until the veggies are just cooked but still have a crunch to them.
Remove the lemongrass stalk, Add torn Thai basil.
Serve over rice with more garnishing of basil and fresh coriander leaves.