In a heavy bottomed pan, heat 1/2 tsp oil. Roast the chana dal and tur dal on medium flame, constantly stirring, until they turn light brown and aromatic. This will take around 8 minutes. Remove this into a dish to cool.
Dry roast the whole flaxseeds over medium flame for 3-5 minutes, until you begin to hear popping sounds. Remove this and keep aside to cool.
In the same pan, roast the sesame seeds for 1 minute, until you get a toasty aroma and they start popping. Remove this and keep aside to cool.
Heat the remaining 1/2 tsp oil. Break the dried chillies into halves and roast them for 3-4 minutes on low flame until they turn bright red and crisp up. Allow this to cool.
In a mixer jar, first grind the fried red chillies with salt. Add the chana dal, tur dal and grind until coarsely ground.
Add the flaxseeds, sesame seeds and pulse a few times until coarsely powdered.
Remove into a dish and cool. Fill this into an airtight bottle.
To mix the podi, add required quantity of gingelly oil (South Indian sesame oil) or for the calorie conscious people, you can mix the podi in dahi (yogurt) and eat with dosas or smear over the idlis.