Dry roasting spices
Dry Roasting or Bhunao is the process of cooking spices (ground or whole) at high heat on an unoiled frying pan for 2-3 minutes until they darken and smoke a bit, then adding small quantities of liquid (water or dahi) when the spices start popping or sizzling, just before it begins to stick to the bottom. It is vital not to let the spices burn. Adding the liquid lowers the temperature and allows you to scrape the pan's bottom and side. This should be repeated a couple of times.
Dry roasting concentrates to essential spice flavours and gives the spices a delicious toasted flavour.
Ground spices are just as good to use as whole spices for dry roasting as long as they are fresh and not jaded. In fact, ground masala was traditionally what was used during the bhunao process.
If you're roasting the spices before grinding, follow the above but do not add liquid. Allow to cool, the grind. Alternatively, the spices can be toasted in an oven preheated to 220C. Toast in your oven until dark and aromatic, stirring occasionally. This can take 7-10 minutes.