We tend not to do a lot of deep-frying as consuming too much deep fried food regularly causes negative impact on health and so we intentionally limit this cooking method to once a month or less.
In general, flour is commonly used for deep frying as it's the most inexpensive option. However, we find that it leaves a lot of burnt residue in the oil and the food gets burnt easily even with a low fire, which makes the dish even more unhealthy. Fortunately, we discovered potato starch, rice flour and tapioca flour which are great alternatives to plain flour. Our personal preference is potato starch and this wheat free option doesn't create burnt remnants in the oil leaving the oil as clear as its original form. Based on research, plain flour also absorbs big amount of oil when cooking causing the food to be high in calories and fats whereas potato starch or even corn starch prevents oil absorption making it the better solution for deep fried foods.
Happy to say that the Sweet and Sour Chicken and Marmite Chicken that we prepare are coated in potato starch batter which are the healthier option as well as also suitable for gluten free diets. A great peace of mind.