Cut up the chicken in an oven dish. Pour it with plenty of citrus juice (freshly squeezed). Then roll well and sprinkle it with soya sauce. Do not add salt - the soya sauce will provide a sufficiently salty taste and you risk oversalting the dish. Optionally, add some black pepper.
Let the marinated meat sit for at least 20 minutes. While it takes in the marinade, prepare the potatoes. Blanch and cut them as you would for frying, but not too thin. Put them in an oven dish. In a cup, pour in some olive oil (or oil ) and add the oregano and chili to taste. Sprinkle the potatoes themselves evenly with black pepper, salt and a little paprika (optional) and add a cup of water.
Put both oven dishes in the oven at the same time and from time to time, change their positions. For the chicken - at intervals, turn the pieces over and pour on marinade. For the potatoes - when they start to turn red, spray them with a mixture of olive oil, oregano and chili.
Serve the grilled chicken with spicy potatoes while still warm.