Soak the rice in cold water for 45 minutes, then drain and rinse until the water runs clear.
Melt together the butter, milk, and saffron in a small pan. Put the dal in a medium pan, cover with cold water, and bring to a boil.
Make a spice paste with garlic, salt, chillies, coriander, ginger, ground spices, yoghurt, and lemon juice.
Prepare the vegetables by cutting them into desired sizes. Toss the vegetables with the yoghurt mixture.
Cook the rice until al dente. Drain well and mix with dal and spices.
Par-cook the vegetable mix in a casserole dish over a medium-low heat for 5-7 minutes.
Pile the rice and dal mixture on top of the vegetables, pour saffron-infused milk and butter over the surface.
Seal the casserole with a dough sausage and lid. Bake in the oven for 30 minutes.
Fry the sliced onions until golden and crisp.
Serve the biryani by removing the lid at the table, topping with crisp onions, flaked almonds, sultanas, and coriander or mint.
