Potato in tomato-yogurt gravy

Ingredients:

1. Potatoes - 6-7 medium sized potatoes.
2. Onion - 1/2 a big onion (cut in small pieces)
3. Tomatoes - 4 medium sized (cut into small pieces)
4. Green chilies - 2 (slit them)
5. Ginger - 1 inch piece (shredded)
6. Red chili powder - 1 tsp (add more if you want it more spicy)
7. Turmeric powder - 1/2 tsp
8. Garam masala - 1 tsp (I used MDH garam masala)
9. Cumin seeds - 1 tsp 
10. Ajwain - 1/2 tsp
11. Yogurt - 1 cup
12. Salt to taste
13. Oil - 2 table spoons
14. Lemon juice - 2 tsp (optional)
15. Coriander for garnish

Method:

1. Pressure cook the potatoes for 2-3 whistles. Remove the skin and cut them into cubes.
2. In a pan, heat oil and add cumin seeds and ajwain.
3. When it starts to sizzle, add ginger and green chilies and saute for a few seconds.
4. Add the onions and saute till they become transparent. Add little salt for the onions to make it cook faster.
5. Now add the tomatoes and let it cook till they become soft and mushy. Add little water if you think its starting to stick to the pan.
6. Add red chili, turmeric powder and garam masala. Let this mixture boil . Add more water for a gravy consistency.
7. Add salt. 
8. Now add the potatoes and mix well. Cover the pan and let it boil for about 5-7 mins.
9. Turn off the flame and add the yogurt. Mix well and garnish with corriander and lemon juice.
10. Serve hot with chapatis.