Prepare the idiyappam and let it cool completely. You can also use pre-made or store-bought idiyappam. Crush with your fingertips into smaller broken 'noodles'. Measure out 4 cups and set aside.
Heat 2 tsp oil and add 1/2 tsp mustard seeds.
When they pop, add the broken cashew nuts. Roast until golden brown.
Then add the grated ginger, green chillies, and curry leaves. Saute until the ginger turns fragrant and the chillies turn softer - about 1 minute
Now add turmeric powder, lemon juice, and salt. Mix well.
Add the sevai or idiyappam
Mix well and make sure the flavours are balanced well. Adjust salt or lemon juice as required. You can also add a pinch of sugar
Serve warm with coconut chutney
Notes
You can use peanuts instead of cashew nuts
Garnish with coriander leaves if you have some handy
The green chillies can be replaced with dry red chillies torn into pieces
You can use lime or lemon for tangy-ness but Indian lime tastes the best
A pinch of sugar can be added, this is purely optional
Some split urad dal can be added along with the cashew nuts and roasted, gives a nice toasty flavour to the lemon sevai