This sambar is specially prepared on occassions and goes well with idli and dosas. The term ‘arachuvitta’ means to grind. Here the coconut and spices are sauteed and ground which gives this sambar a distinct taste.

Ingredients to be ground to make the paste 
Fry the chana dal, coriander seeds, pepper, fenugreek seeds and red chillies 
Add coconut and saute till it becomes slightly golden in colour 
Transfer to a mixie 
Grind to a smooth paste 
Veggies and tamarind required for sambar 
Boil the vegetables separately 
After it is cooked, add the ground paste and cooked dal into it. 

Ingredients:
For Paste
Coriander seeds – 2 1/2 tbsp
Red chillie – 5
Bengal gram dal/Chana dal – 1 tbsp
Fenugreek seeds – 1/4 tsp
Whole pepper – 1/2 tsp
Fresh grated coconut – 1/4 cup
Raw rice – 1/4 tsp
For sambar:
Tur dal – 1/2 cup
Tamarind – 1 small lemon sized ball
Shallots – 6 -7
Tomato – 2 small
Carrots – 1/2
Ladies finger – 4-5
Brinjal – 2 small
Drumsticks – 1 long (cut into 5 – 6 pieces)
Coriander leaves – 1 tsp chopped (for garnish)
Jaggery – a small piece (optional)
Oil- 1 tbsp (preferably gingely oil)
Salt – to taste
For seasoning:
Oil – 1/2 tsp
Mustard seeds – 1/4 tsp
Asafoetida – a pinch
Jeera/Cumin seeds – 1/2 tsp
Curry leaves – 2 sprigs
Preparation:
Soak the tamarind ball in 1/4 cup warm water for 10 minutes. Squeeze it out well and strain the pulp. Keep it aside.
Take a pressure cooker and add the cleaned tur dal to it. Add about 1 1/2 cups to it and cook for 3 -4 whistles. Remove and when the pressure is released, mash the dal well and keep it aside.
Meanwhile, prepare the paste. Take a pan and add the bengal gram dal and coriander seeds. Saute it well and add the fenugreek seeds, pepper and the red chillies, Fry it well for 3 – 4 minutes and then add the coconut lastly. Roast for a few seconds till it turns slightly brown. Remove from fire and let it cool. Transfer to a mixie and let it cool. Grind to to a smooth paste (some like it to be a coarse paste).
In another pan, add all the vegetables and 1/4 cup of water and let it cook. When it is almost cooked, add the tamarind pulp and boil once. If you are using jaggery, add the jaggery. Then, add the mashed dal and the ground paste to it and on a medium flame, let it simmer for 3-4 minutes.
Season the sambar with the ingredients mentioned ‘under seasoning’. Garnish with coriander leaves.