Peel the potatoes, cut them into 1 inch cubes. Wash them, and then put them in a pan. Cover them with water and add 1 tsp. salt. Bring to a boil and let them simmer on medium heat until the potatoes begin to soften. Do not over-boil, they should be done but still firm or else they will get mashed when mixing the salad.
Drain and put the potato cubes in a bowl. Squeeze in the lemon juice, quarter tsp. salt and red chilli powder. Add the chopped red onion and green chillies. Toss them gently to combine. Set this bowl aside for the potatoes to cool completely. To speed things along, you can pop the bowl of potatoes into the fridge until they are cool. If the mayonnaise is added onto the hot potatoes, it will thin out and you will lose the thick creamy consistency, so don't omit cooling the potatoes.
In the meantime, in a bowl, mix the mayonnaise, yoghurt, garlic paste, black pepper powder, chilli flakes, cumin powder, sugar and salt. Whip it well with a fork until smooth and well combined.
Put the chopped cucumber in a kitchen towel or tissue and squeeze out any excess water. Then add the cucumber into the mayonnaise mixture and stir.
Once the potatoes are cool, add the chopped boiled eggs and chopped coriander, then pour in the mayonnaise mixture. Gently stir everything together to combine. Sprinkle some spring onions and a dusting of either paprika or red chilli powder. Taste and adjust.
TIP: You can omit the boiled eggs and have a plain potato salad, or use chopped cooked sausages, or shredded chicken for variety.
This salad is best served cold, so you can keep it refrigerated until time of serving.