Peel, wash and cut potatoes into big chunks. Peel carrots, kohlarabi and beetroot, wash them and cut into thin dices and keep them aside separately. Cut beans each into 2 pieces. Separate cauliflower florets, wash, towel dry and keep aside.
Deep fry all the vegetables separately and lastly the beetroot to avoid colouring the oil. Do not fry the green peas.
Pre soak the basumati rice for half an hour after rinsing the rice at least 3 or 4 times or until the water runs clear. For golden sela rice, it has to be soaked for 2- 4 hours.
Heat the vegetable oil in a pot. Add the whole spices – 10 cloves, 10 green cardamoms, and 2x 3″ cinnamon sticks. Peel, wash and slice 5 large onions and fry them on medium heat with the whole spices till they are golden brown.
Add ginger garlic paste, turmeric and red chilly powder followed by green chillies and tomatoes. Turn over and cook till they soften a bit. Add yoghurt, throw in a few mint leaves, fresh chopped cilantro and combine everything to get a thick smooth sauce like consistency.
Now add all the fried vegetables and green peas, sprinkle 1 tsp lemon juice, adjust the salt and mix all the vegetables with the sauce well.
Bring a pot of water to boil. Add the basumati rice and 2 -3 tbs of salt. Cook for a few minutes till the grains are 70 % done. You can test this by picking a grain of rice and pressing it between your index finger and thumb to see how much it is cooked. If you see 3 white dots inside while it feels a little soft on the outside, it means it is time to stop cooking. After the first boil you should keep checking the rice from time to time by doing this test. The time taken to cook the rice differs with each variety. So you have to be very alert and careful as this is a crucial step which cannot be overlooked. Drain the rice in a colander.
Meanwhile transfer the vegetable sauce to the roaster and place it in the oven pre-heated at 375ºF. Dissolve a few strands of saffron in warm milk and keep it ready.
Layer the cooked rice over the sauce in the roaster. Top it with the reserved fried beetroot pieces, fresh mint and chopped cilantro. Add a pinch of edible orange food colouring on one side and mix it with a little rice then sprinkle the coloured rice over the white rice. Sprinkle saffron milk. Cover the roaster with its lid and steam in the oven for 10 mins.
When done switch off the oven, take the roaster out and leave it to rest on the counter for 5 minutes. By now you should be able to feel a whiff of the aroma in the air. Uncover the roaster lid slowly and gently mix the rice with a round or flat spatula by scooping the vegetables and sauce from the bottom and then layering over the rice. Combine everything well. We usually don’t mix the whole roaster at one go. There’s a specific technique of mixing the rice with the sauce which is to be followed to avoid breaking the rice and vegetables. That is why it is done very gently. We serve as we mix. After serving you could put back the roaster in the hot oven (but not switched on) till you serve again. This way the biryani remains hot till the end. Enjoy the vegetable biryani with onion yoghurt chutney.