Add some oil in a heavy bottom pan. Add cumin seeds and let it crackle in oil for a while.
Add chopped onion and stir-fry until they get a golden brown shade. Add chopped tomatoes and stir again.
Now, put usual Indian spices like turmeric (1tsp), dry coriander powder (2tsp), red chili powder (1tsp), garam masala powder (1tsp) and salt to taste. Cook the tomatoes well.
Enjoy it with hot chapattis.
Simply add some water to the dish mentioned above and let it boil for some time. This way, you can give a new touch to this dish.
In case you have shallot onions, which are extremely small onions, you can make Pyaz Curry out of these. For that, you need to take a heavy bottom pan, add onions along with usual spices such as turmeric, salt, red chili powder, garam masala powder and cover with a lid. After 5 minutes, check whether the onions are cooked. Then you may saute them again and add garam masala powder for enhanced aroma and flavor.
These are a few recipes, one can try using tomatoes and onions only. Also, if you do not like to eat pieces of any of these viz. tomatoes and onions, you may grind them into a paste and then use it for preparation of a curry.