Heat a thick bottom pan. Now add coconut oil, heat the oil on medium to low heat. After the oil gets heated, add methi seeds. Fry well on medium low heat, methi seeds should turn light golden colour.
Next add cumin to the frying pan. Again, fry well on low heat until you get nice aroma or well cooked in oil.
Now add the third spice coriander seeds, this also needs to be fried well on low heat until they become crisp and lightly golden.
At the end add red chilies and fry well on low heat for 5 to 10 minutes or until they become crisp. If they are not crisp, they do not get powdered well. So, fry till they are perfectly crisp.
Let all the fried ingredients cool down to room temperature. Transfer the cooled ingredients into the dry mixer jar and make a fine powder using a dry mixer jar.
Fresh aromatic Udupi style rasam powder or sarina pudi is ready to be used. Cool the powder and store it in airtight glass jar. Use this rasam powder to make tomato saru or rasam.