Start by making the sauce. Add your boiling water and rice vinegar to a medium sized saucepan and bring to the boil.
Add your sugar, garlic-infused olive oil, ginger purée, chilli purée and low FODMAP ketchup and stir for 1 minute.
Simmer for 10 minutes and then stir in the cornflour mixture.
Set aside for later.
To make the gluten free batter, mix all of the dry batter ingredients in a bowl and slowly add the water until it's the consistency of single cream (not too thin/watery, not too thick and gloopy).
Mix your chopped chicken breast in the gluten free batter mix until well coated and put to one side.
Time to heat your oil. If you don't have a deep-fryer (it's not mandatory!) start by pouring your vegetable oil into a decent-sized saucepan. You want around 1-1.5 inches of oil in your saucepan. Heat this at a medium heat until it reaches 190c or 375f. If you don't have a cooking thermometer then just drop a little batter in occasionally - if it sizzles and browns quickly, it's good to go. If it sizzles but doesn't brown, it's not hot enough. Smoke and violent bubbling means it's too hot!
Once it's reached the desired temperature, carefully lower each chicken chunk into the oil one at a time and be wary of splashing the oil (I use chopsticks to do this, but anything apart from your fingers will do). The oil should be lively and bubbling around each chicken chunk, but not noticeably spitting at all. Don't put too many in at once (I put 6-7 in at once max in a large saucepan) and try to use a slotted spoon to separate them early on if they stick together. Cook each chicken chunk for around 4-5 minutes.
After 4-5 minutes, they should be nice, light and airy and a light, golden colour. Remove them from the oil with a slotted spoon and drain them onto kitchen paper. Repeat until all of your gluten free battered chicken is cooked.
Put your gluten free battered chicken into your sauce and serve immediately. Enjoy!