• Wash and soak rice and dal separately. Soak the fenugreek seeds along with urad dal. Let this soak for 3-4 hours. 
• After the said time, drain the water from urad dal and grind it to a fine batter in a grinder. It takes almost 20-30 minutes for the dal to grind to a fine, aerated batter.
• The batter makes a 'cluck,cluck' sound, the sound of a well aerated, fluffy urad dal batter. Remove the batter to a clean vessel.
• Now drain and add the rice to the grinder, add the fresh turmeric root along and grind it to smooth batter. Once it is done, remove the batter to a clean vessel and mix both the batter together. 
• I normally add the ground urad dal batter back into the grinder, when the rice is almost done. So both the batters get mixed well in the grinder itself.
• Remove the batter to a clean vessel, that is wide enough, to hold the fermented batter. Fermentation will cause the batter to raise a bit. 
• Let the batter sit overnight or atleast 6-8 hours to ferment. The batter would be well risen if it has fermented well.
• If making dosas immediately, remove the necessary batter to another vessel and refrigerate the remaining batter.

To make the dosa

• Add salt to the batter and mix well. Heat a flat tava/dosa pan, add a dab of gingely oil and wipe it well on the pan with a paper towel.
• Pour a ladle of batter in the center of the tava, and slowly spread it circles using the back of the ladle. Dot the edges with gingely oil, let it cook on one side for a minute or until the edges turn brown.
• Flip and cook on the other side. Serve it hot with any chutney/Sambar of your choice. My kids usually prefer idly podi and mint chutney with their dosas.