Marinate chicken: Slice the chicken breasts into 1-inch/ 2 cm pieces. Grate the garlic, chili, and ginger. Place everything in a bowl, add the curry powder, oil, and vinegar, mix well, cover the bowl, and marinate for about 1-2 hours.
Prepare rhubarb: In the meantime, clean the rhubarb and cut it into 1.5-inch/ 3 cm pieces. If the rhubarb stalks are too wide, cut them lengthwise first and then into smaller strips. Slice the unpeeled apple thinly and chop the onion finely.
Saute rhubarb: Heat the skillet and melt the coconut oil. Add the rhubarb, apple, and onion and cook for about 2-3 minutes, stirring gently. Add the honey, stir again, and remove everything from the pan.
Cook chicken: Wipe the pan clean with a paper towel. Remove the chicken slices from the marinade and cook them in 2 batches, about 2-3 minutes for each batch. Stir a few times to make sure that the chicken browns on all sides.
Simmer rhubarb curry: Return the rhubarb-apple mixture back to the pan, add the raisins and the coconut milk, reduce the heat to medium-low and simmer for about 10 minutes, the sauce should thicken slightly, the chicken should be cooked through and the rhubarb should be soft but not mushy. Serve with rice.