Rinse and take tomatoes, onion, halved or quartered, 15 to 18 cashews in a heat proof bowl.
Pour 2 cups of hot water. Cover and blanch these ingredients for about 25 to 30 minutes.
Meanwhile, rinse or wipe dry the mushrooms. Slice or chop them. Rinse, peel and chop the potatoes in small cubes. Keep aside.
After 25 to 30 minutes, drain and chop the tomatoes roughly. Add the tomatoes along with their juices, blanched onions, cashews in a grinder or blender jar.
Also add 1 tbsp chopped coriander leaves. Without adding any water, grind to a smooth fine paste. Keep aside.
making aloo mushroom
Heat 2 tbsp oil in a pan. Add the whole spices - 1/2 tsp caraway seeds/shahjeera or 1/2 tsp cumin seeds/jeera, 1 medium sized tej patta, 3 cloves, 2 green cardamoms, 1/2 inch cinnamon and 1 single mace strand.
Saute till the spices crackle and become fragrant.
Then add the sliced or chopped mushrooms.
Stir very well and begin to saute the mushrooms.
While sauteing the mushrooms would begin to loose water.
Continue to saute on a medium flame till all the water dries up.
Then with the spoon, bring the mushrooms towards one side of the pan and add 1 tsp ginger-garlic paste. In the same place, stir and saute the ginger-garlic paste till the raw aroma of ginger and garlic goes away.
Now add the potato cubes. Stir and saute for 2 minutes.
Then add 1/4 tsp turmeric powder, 1/2 tsp red chili powder and 1 tsp coriander powder.
Mix the spice powders with the rest of the ingredients.
Add the ground paste. Stir and mix well.
Saute for 5 to 6 minutes on a low to medium flame or till you see some oil releasing from the sides.
Then add salt as per taste.
Add 1 to 1.25 cups water. Depending on the gravy consistency you want, you can add less or more water. Stir very well.
Cover and simmer the gravy on a low to medium flame till the potatoes are cooked through. It takes about 12 to 15 minutes. Do check at intervals and if the gravy becomes too thick, then add some water.