Heat oil in a heavy-bottom pan over medium heat. Add cumin seeds and let them splutter.
Next, add minced ginger, garlic, and green chili, and saute for a few seconds until fragrant.
Then add onions and saute until the onions turn light brown.
Next, add chopped tomatoes and cook till they are soft and mushy.
Add the dry spices like turmeric powder, red chili powder, coriander powder, and garam masala and cook for another 2 minutes till the masalas are cooked well.
Add diced potatoes, mix well, and saute for 2-3 minutes.
Add ¼ cup of water. Mix well. Cover, and cook the potatoes for 6 to 7 minutes on medium-low heat until they are fork-tender. You may stir occasionally once or twice in between.
Then add diced eggplant (brinjal) and mix well.
Cook covered for another 5 to 6 minutes (keep stirring in between occasionally), until the eggplant and the potatoes are perfectly cooked. You can add some water to cook if needed.
Lastly, add kasuri methi, lemon juice and mix very well. Turn off the heat.
Garnish with cilantro (coriander leaves), and serve with roti or paratha.