Remove excess fat from the chicken while keeping the skin on. Season generously with salt, pepper, paprika powder, and curry powder.
Heat a casserole dish with a lid over medium-high heat. Add some fat and sear the chicken on all sides until browned, about 8-10 minutes.
Reduce heat to medium-low and add the 500g light-colored seedless grapes to the pot.
Cover the casserole with the lid and steam for 40 minutes. Check occasionally to prevent burning. Gradually add the 0.25 liter water throughout the cooking time.
As the grapes burst during cooking, they release juice that forms a sauce. Once the chicken reaches an internal temperature of 74 °C (165 °F), pour in the 2 tablespoons of soy sauce.
If desired, bind the sauce with the dark sauce thickener according to package directions, and season to taste with five-spice powder.