Cut 2 big tomatoes (unripe ones better) into medium pieces.
put them in a vessel and simmer (magginchu) for 5 min. until skin separates.
cut green chilis (4), keep aside
Make tamarind paste (1/2 to 1 spoon) 
In a separate vessel, pOpu (oil fry)
- heat oil,
  add pinch of hing (inguva),
  add 2 red chilis, 1/2 teaspoon chana dal (sanaga), 
  add 1 teaspoon urad dal (minapa), 
  add mustard (AvAlu) after it starts spattering,
  optional: add curry leaves (karivepAku)
  add cut green chilis.
  after they turn color, remove from heat.

blend above tomatoes, oil fry, tamarind paste, salt to taste, 1/2 spoon sugar 
in a blender.  Not too much.  At most 5-6 seconds.

tomato pachchaDi is ready.

This is the standard recipe for almost all vegetable-based short-term 
pachchaDis like 
- vankaya-tomato
  donDakaya, 
  dosakaya etc.