Indian foods uses a lot of spices. Almost in a level that you will find one new spice in every new recipe.
Still the most common spices AFIK are the follows in the decreasing order of frequency of use
- Turmeric powder
- Coriander powder
- Cumin powder and seeds
- Chili powder (You can replace with green chilies if you must)
- Garam masala
- Dried red chilies
- Black peppers
Also asafoetida, fresh coriander leaf, whole cumin seeds, whole mustard seeds. Also, if you can get some ajowan, get it: While not useful in every recipe, it is really great in eg samosas and tikka marinades.
Also, these are very commonly used ingredients
- Green chili peppers
- Cashew nuts for added thickening (as a paste of boiled cashew nuts) or whole as an ingredient (or both - cashew-thickened real korma with sundry vegetables, dried fruits, and whole cashews added is mind blowing - bring on the saffron too!).
Also always make some yogurt (Unflavored and unsweetened) available
Most common vegetables are
- Bell peppers (Green)
- Red Kidney Beans
Most common grains are
- Rice (Basmati rice is considered as delicacy)
- Dal (Many varieties, but you might need mung bean, lentil, toor daal, urid dal )
- Whole wheat flour and normal flour
Traditionaly different kind of oils are used but now a days mostly vegitable oil is used. You will also need ghee (Similar to clarified butter) to make some complex and rich dishes.