Boil potatoes and carrots in a pot of boiling water for 3-5 minutes until just tender. Drain and set aside.
Heat oil in a wok or frying pan. Saute onions until fragrant. Add Masaman curry ingredients and bring to simmer. Add chicken and pan-fry until browned.
Add in masaman curry sauce, potatoes and carrots. Allow to simmer for 15-20 minutes.