The Platts dictionary gives
H طاهري t̤āhirī (prob. fr. t̤āhir) , s.f. A dish of rice and adaurī, q.v.; rice cooked with turmeric.
I normally look up the origin of a food dish in the dictionary to get a sense of the dish.
Tahiri comes from Hindi and is a very Hindustani dish and one of my favorites. It is a vegetarian variation of a pulao.
As you saw there are two definitions for it. One that it’s cooked with turmeric, the other that it has adauri ( lentil baris). I prefer to add potato and peas and accompany it with dahi and green coriander chutney.
Ingredients
2 medium cup rice ( I always measure rice by cups as its easier to add water for each grain of rice to be separate) Soak rice for two hours.
2 potatoes – cut in 4
1/2 cup shelled peas
1/4 tsp Nigella seeds
2 cloves ( laung)
1 tez Latta ( bay leaf)
1/2 tsp pepper corns
1 heaped tsp turmeric powder
1 tbsp ginger / garlic paste
Salt & chili to taste
Oil
Method
Heat oil, add the Nigella, pepper, clove and bay leaf. Saute for s minute and add the other masalas. Add dashes of water to Saute it.
Add potato and peas and saute for a bit.
Add rice, salt and chili ( green – whole or red chili powder) as per taste.
Add exactly double the amount t of hot water as rice.
For example if 2 cups rice then 4 cup water. ( Same cup)
You can pressure cook – 1 whistle – 5 Minutes or cook in a pateeli.
If in pateeli, put on Sim once water boils. and as water is hot should happen fast.
Once water is soaked in rice, put a griddle under the pateeli ( pot) and leave it on dum ( Sim) for 5 Minutes.
Rohini Kaul sent me this information on Instagram which I am adding:
Monjahar Tahar is one of the ancient festivals that was followed by Kashmiri Pandits.
Monjhar means lunar month of Margashirsha and Tahr is the yellow rice which before serving is mixed with mustard oil and coarse salt. Tahar is cooked on the first day following the end of Margashirsha which marks the beginning of Paush/ Posh month. This yellow rice is specially cooked for Ghar Devta / Griha Devta and then distributed among all the family members and neighbours.
It is also believed that celebrating this day brings luck and success to the family. Hence, many times the family members pray to the Ghar Devta that if their wishes are fulfilled they will offer him Tahar every year.
Tahr /Tahri, turmeric rice is also cooked on multiple occasions, especially on our lunar calendar/tithi birthdays/kashmiri birthdays & is offered to god & birds/insects first. It is considered as the main Prasad. Generally served with Dum Aloo, Chaaman kaliya(curd turmeric paneer), Nadru yakhni (lotus stem curd curry) and many kashmiri dishes.