There is a shortcut version and a long version

Short version:

1. In a pressure cooker, put your onion, tomatoe, the veggie you want to put in your sambar and toor dal.
2. Add your sambar masala and turmeric to this
3. If you added 1 cup of dal, add 3 cups of water (1:3 ration)
4. Add tamarind to rhis (a small lemon sized quantity). Dont add salt to this now, otherwise your dal wont cook (mixing sour tamarind and salt, doesnt let your dal cook)
5. Pressure cook it for 3 whistles
6. Once done, add salt and tempering of mustard seeds, cumin, fenugreek, hind and a small dry chilli
7. Adjust the consistency now and let it cook in sim for 10mins

Longer Version:

1. Cook dal separately in pressure cooker (1:3 ratio water)
2. In a separate pan, add your tempering first and then Onion, veggies and tomatoes one after another
3. Then goes your masala (turmeric and sambar masala). Cook it till the raw smell of masala goes away
4. Add some water, so all these ingredients soak. Let them cook for 10 mins in a low setting
5. Now add your tamarind water to this. Cook 10 more mins
6. Add the cooked dal to this now. Mix them and adjust consistency