Combine raii, heeng and methi seeds.
Heat a pan and dry roast over medium heat stirring till fragrant about 3 minutes.
Cool and grind to coarse powder.
Put sliced chili in a bowl. Add spice powder, haldi, salt and stir to coat chili nicely.
Pour this mixture in a sterilized jar. Set aside overnight, at room temperature.
Next day heat oil to smoking point at medium heat.
Pour slowly over chili spice mixture. It will foam and sizzles. Let it cool.
Cap jar and set in sun for a day.
Next day add enough lemon juice to cover chilies.
Cap and put in sun again for 3-4 days.