Cook the potatoes until they are fork tender. Peel them and then chop into 1 inch cubes and keep it aside until ready to use.
Wash and chop the eggplants into 1 inch cubes.
Heat 1 tablespoon of oil in a wide pan and add the chopped eggplants. Sauté it on medium high heat until the eggplants becomes light brown. Gently stir the vegetables when sautéing. Do not cover the vegetable with a lid at any point. This step ensures that the eggplants do not become mushy. Also sautéing the eggplant helps to retain the texture of the vegetable when we add it in the gravy. If we directly add the vegetable in the gravy and cook, the eggplant would become all mushy. Remove the eggplants with a slotted spoon and leave it aside.
In the same pan, that we sautéed the eggplants, add the remaining oil and heat it. Add the cumin seeds and let it splutter. Now add the sliced onions and sauté until golden brown.
Add all the spices – turmeric powder, chili powder, dhania jeera powder, garam masala and salt.
Add the chopped tomatoes and mix well. Mix well and cook on low-medium flame until the oil separates from the mixture. This could take about 10-12 minutes. Be patient and stir it every now and then to avoid burning at the bottom.
Now add the fried eggplants and boiled potatoes and mix well. Add water to adjust the gravy and let it come to a boil. Simmer for about 10 minutes to allow the flavors to combine. Check the seasoning and then garnish with cilantro.
Serve Aloo Baingan Subzi hot with paratha, poori or rice!