In a large pot, bring water to a boil and add the mixed vegetables and diced potatoes. Cook them until they are tender, about 10-15 minutes. Drain the vegetables and set them aside.

In a skillet, heat oil over medium heat. Add the chopped onion and cook for 2-3 minutes until it is translucent.

Add the minced garlic and grated ginger to the skillet and cook for another 1-2 minutes until fragrant.

Add the tomato puree to the skillet and stir well. Add the ground cumin, ground coriander, garam masala, turmeric powder, and salt to taste. Cook the mixture for 10-15 minutes until the sauce thickens.

In a food processor or blender, blend the cashews with 1/4 cup of water until you get a smooth paste.

Add the cashew paste and coconut milk to the tomato sauce in the skillet. Stir well and cook for another 5 minutes.

Add the cooked vegetables and paneer (if using) to the skillet. Cook for another 5-10 minutes until everything is heated through and the flavors have melded.

Garnish the Navratan Korma with chopped coriander leaves and serve hot with rice or naan bread.