If I ask you to prepare one recipe that goes well with everything -- Idli, Dosa, Chapati, and Poori, I am sure the first recipe in your list would be this Tomato Pachadi. This is mostly referred to as Bachelors' Recipe (perfectly referred, am I right??) as this is easy and takes very less time to prepare, yet delicious.
Cumin ¼ tsp
Large Ripe Tomatoes 3
Sambar Powder 1 tbsp (leveled) or to taste
Salt ½ tsp or to taste
Chop Onions lengthwise. Cut Tomatoes into pieces.
Heat Oil in a Pan. Add Cumin. Let them crackle and add Onions. Fry till Onions turn translucent. Add Chopped Tomatoes and Salt. Fry on a medium flame till the oil separates and the raw smell goes off. (approx 10-15 mins)
Serve hot with Idli or Dosa or Chapati or Poori. This can also be served with Rice.
Note: 4-5 Green Chillies can also be used instead of Sambar Powder. Curry Leaves can also be added as seasoning. I haven't added as I get it rare.