When it starts popping, add the remaining dals and fenugreek to it.
Keep the heat low-medium.
You do not want to burn the dals, especially fenugreek which turns bitter when even slightly burnt.
When the dal gets reddish brown, add the onions.
Add salt and asafoetida and give it a stir.
At this point, as the onion is getting soft (around 3-4 min mark), the aroma that wafts from this mixture is so typical of a South Indian household.
Add the water along with curry leaves.
You can also add them along with onions instead of now (or do 50-50).
Increase the heat to med-high.
When the water starts boiling, add the tamarind paste.
In around 2 minutes, add the sambar powder.
Stir until combined and continue cooking until the raw smell of tamarind is replaced with a tangy aroma.
You can at this point continue cooking (simmering) for another 6-7 minutes until the mixture thickens or (after reducing heat to low-med) mix 1 tsp of rice flour along with 1 tbsp cold water into a paste and add it to the stew.
This will thicken it in less than 1-2 minutes.
Serve this with steamed rice.
1. You can use shallots/Pearl onions for this.
2. The amount of tamarind paste will vary depending on the brand you use and the taste.