While adding tamarind extract be cautious otherwise it will become more tangy.
I add garlic but its optional.
I have used Bangalore tomatoes and if the tomatoes itself is tangy then reduce the tamarind extract.
I don't add turmeric during pressure cooking dhal,usually I add it later.
I some time add red-chillies for tadka and sometimes I skip adding.
Adding vadakam gives special flavour to this sambar.