Add the sesame seeds to a kadhai/wok and roast them till you get a popping sound. pop. Transfer to a big plate to cool. (Check notes 1)
In the same kadhai/wok add ½ teaspoon oil and the red chillies. Stir-fry them for 2-3 minutes on low flame till it begins to get a darker colour. Take care not to burn them.
And again add to another plate the plate and let them cool.
In the same kadhai/wok add ½ teaspoon of oil and fry the Chana dal. Let the dal turn golden brown. Transfer to the plate in which you have added the sesame seeds and let it cool.
Similarly, add ½ teaspoon oil and fry the urid dal till golden in colour. Let it cool on the same plate with the chana dal.
Add oil and roast the flax speed till you get a popping sound. Let them cool too.
Meanwhile, your chillies will have cooled. Transfer the chillies to a mixer and blend to a very coarse powder.
Add the sesame seeds, dals, salt and flaxseeds and blend to a coarse powder.
Transfer to an air-tight container.
Enjoy with idli, dosa, etc!
Notes
If you like me store your sesame seeds after roasting them then you can avoid roasting the sesame seeds or til.