Preheat oven to fan 180°C, conventional 200°C, gas 6.
Heat oil in a large flameproof oven dish and brown chicken thighs on both sides.
Remove chicken thighs from pan and set aside.
Add potatoes to pan and fry in remaining oil for 2 minutes. Remove potatoes from oil using a slotted spoon and drain excess fat from dish.
Return chicken and potatoes to dish, pour over ratatouille, sprinkle over oregano and tumble ingredients together to combine.
Place in the oven for 30 minutes or until chicken is cooked though, stir halfway during cooking.
This recipe can be cooked on the hob for 30 minutes, or until the chicken is cooked.
This recipe can be frozen. Defrost thoroughly in a refrigerator prior to reheating.