The five spices that make up Panch Phoran are:
Mustard seed or (rai or shorshe)
Fennel seed (saunf or mouri)
Cumin seed (jira)
Nigella seed (kalonji)
It's also said that another spice called radhuni is used in place of mustard seeds. However since these seeds are not widely available, it's mostly mustard that's used.
Though this spice blend is never added as a powdered form to curries or other dishes, dry roasted panch phoran is ground and used for sprinkling on chutneys. Paanch is five in hindi & Bengal and Phoron refers to spices in Bengali. Panch phoran is used mainly for tempering, to flavor the hot oil before adding rest of the ingredients.
Panch phoron is added to the hot cooking oil before adding any other ingredients thus flavouring the oil and releasing the aroma of the seeds and causing them to pop in the pan. At this point the other ingredients are added.
You can easily make this at home yourself if you have all the five spices on hand. Take all the spices in equal measures, except for methi as it turns bitter when added more.
Mustard seed - 1 tsp
Fennel seed - 1 tsp
Cumin seed - 1 tsp
Nigella seed - 1 tsp
Fenugreek - 1/2 tsp
As I always think, the culinary expansion depends on how much a particular ingredient is popularized. Same as Panch phoran, we have a similar spice blend in south that's common for tempering. I am not sure about other households, but I have always seen Amma having different spice blends ready for use.
South Indian spice blend that I shared many years ago, showcases what we use for making Sambar. Amma also had a similar one mixed for dals, tamarind base gravies etc.
The Whole Spice Blend For Tempering made in south India for Sambar has the following spices
Mustard Seeds - 1 tsp
Urad Dal (whole or split) - 3/4 tsp
Cumin Seeds - 3/4 tsp
Methi - 1/4 tsp
Amma adds channa dal to the above, whereas I don't.
This reminds me that I may have to do another post with the different spice blends we make..:)