Cut the chicken into bite sized pieces and pop it into a mixing bowl.
Add the soy sauce, mirin, and cornflour into the chicken and mix it well until it's completely coated.
Cover it with cling film and leave it to marinade for half an hour. Meanwhile you can prepare the other ingredients.
Heat a good amount of oil in a large frying pan and cook the chicken over a medium-high heat until its golden all over.
Once it's cooked, remove it from the pan and pop it onto kitchen paper to soak up any excess oil,
In a clean pan, add a tbsp of cooking oil and a tbsp of sesame oil.
Stir fry the onion over a high heat for a few minutes until it starts to soften, then add in the sliced red pepper and cook for a further minute.
Add the garlic, ginger, spring onions and ground up sichuan peppercorns. Stir fry for 30 seconds. Then add the chicken back into the pan.
Now add in all of the sauce ingredients and stir to coat. Cook for one minute.
Serve immediately with rice and enjoy.