To make the curry mix: Grind the fennel seeds in a mortar and pestle. Add the other spices and combine
Keep in a jar. For this recipe add 1/2 tbsp of mix.
To make the curry: Heat the oil on medium -high in a skillet or small saucepan.
Season the chicken with salt and pepper and fry in the skillet until sealed and going golden, about 4 minutes.
Remove the chicken from pan and set aside.
Reduce the heat to medium and add the onion and cook the onions until they are soft - this should take a couple of minutes or so. If you use an electric stove, it can be slow to cool down and your onions might be fried rather than just softened. This is not a problem in terms of a great tasting recipe.
Add the apple, 1/2 tbsp curry mix, ginger and garlic and cook until fragrant. This takes a minute or two.
Stir in the flour and cook for a minute or two, stirring until well combined.
Add the stock and keep stirring to make sure it is well combined.
Keep stirring until it is boiling then turn the heat to let it simmer for a couple of minutes until the sauce thickens . This should take 2-3 minutes. But keep an eye on it as the smaller amounts may mean it thickens quickly depending on how much your stove has cooled.
Add the chicken back in and stir in the the rice wine vinegar. Cook for about 8 minutes.
Add the baby spinach and cook until the spinach has wilted, about a minute or two.
Garnish with the coriander (cilantro).