Peel potatoes and cut each to half inch slices, Slice each to few half inch sticks. So you will have each stick of about half by half inch thickness. Immerse them in a bowl of water for 30 minutes & drain the water completely.
Boil them in fresh water for 3 to 4 mins until they are slightly cooked but firm. Drain them to a colander.
Sprinkle flour, red chili powder and salt over the drained potatoes. Toss well to coat the flour evenly. If it seems too dry, sprinkle some water.
Heat oil in a deep pan. When hot enough slide the potatoes one by one to hot oil. Deep fry on a medium heat undisturbed for 2 to 3 mins, later stir and fry until crisp & golden.
For extra crispness, you may remove them from oil and refry on a low flame. Later remove them to a wired rack or steel colander.
With a clean cloth wipe dry the soaked potatoes. Spray some oil all over the them. Sprinkle salt, red chilli powder and flour. Mix gently to coat. If it looks too dry, drizzle some oil and mix.
Air Fryer: Spread them in the basket in a single layer and air fry at 400 F or 200 C for 8 to 9 mins. Shake them & repeat for another 8 to 9 mins until crisp and golden.
In the Oven: Preheat the oven to 200 C or 400 F. Grease or line a baking tray & arrange the potatoes. Bake them for 23 to 30 minutes until crisp and golden. Adjust the baking time as it depends on the size of your potatoes and oven.
Optional for extra color and heat: Mix together red chilli powder, red chilli sauce and 2 tsps water to a smooth paste. Keep this red chilli sauce aside.
Heat one tbsp oil on a high heat in a wok or pan. Fry garlic and chilli until they smell good.
Add onions and stir fry for a minute followed by capsicums. Fry until they turn slightly tender yet crunchy.
Add the sugar, red chilli sauce, soya sauce, vinegar & 2 to 3 tablespoons water. Let the sauces begin to bubble.
When the sauce thickens taste the sauce and adjust more salt and sauce if needed.
Turn off and cool down slightly. Add fried potatoes and toss. Add spring onion greens.
Serve chilli potato hot or warm immediately as they lose the crispness if rested. Serve as an appetizer or as a side with noodles and fried rice.