For the Roasted Masala Paste

First, lets make the main prep for this kuzhambu, the roasted masala paste. Heat oil in a pan on a low flame. Add a small piece of cinnamon and cloves. Add the fennel seeds, cumin seeds, coriander seeds, dried red chillies, black pepper, garlic, and curry leaves. Roast on a low flame for a minute. Make sure not to burn the spices.
Add the sliced shallots, a small piece of tamarind (if using) and saute till the shallots are soft and starting to brown.
Add the tomatoes and the salt. Saute till the tomatoes are soft and mushy. Once the tomatoes are mushy, add the fresh coconut and cook for a minute more. Remove the pan from heat and let the mixture cool a bit.
Grind everything with little water to a smooth paste. Set aside.

For making the kuzhambu

Heat oil in a pan and add in the onions and the curry leaves. Saute for a couple of minutes till the onions are soft. Add the turmeric powder and the salt. mix well to combine. Add the diced potatoes if using and add some water to cook the potatoes. Mix well. Cover the pan with a lid and cook for 10 minutes on medium flame.
Add the cauliflower. Add the masala paste. Wash the mixie with water and add it back to the pan. Mix well to combine. Cover the pan with a lid and cook for 10 minutes on medium flame.
The curry is ready. Finish the curry with a generous sprinkling of coriander leaves.
Serve with tiffin items or rice