Bring a large pot of water (at least 4 quarts) to a rolling boil. Reduce to a simmer and add the green and black cardamom, cinnamon stick, bay leaves, and about 1 tablespoon of salt.

Add the rice and cook on low heat for no more than 5 to 7 minutes. Once parboiled, drain immediately into a colander and set aside.

Heat oil over medium-low heat in a heavy-bottomed stockpot. Once it shimmers, add the onions and cook for 10 to 15 minutes, stirring occasionally, until evenly golden brown.

Add the crushed ginger and garlic and stir for about 30 seconds until the raw smell cooks off.

Add the cumin powder, coriander powder, red chili flakes, and turmeric powder. Stir for 1 to 2 minutes until the spices are fragrant. Deglaze with a splash of water if the spices begin to stick.

Increase the heat and add the chopped tomatoes. Stir continuously until they soften and break down, about 5 to 7 minutes.

Add the prawns and cook on high heat for 3 to 5 minutes until opaque and just cooked through.

Add the chopped green chili and cilantro. Remove from heat. Transfer half the masala to a separate bowl.

If using saffron, grind the threads with a pinch of sugar, place in a small bowl, and bloom in 1 tablespoon of warm water.

In a separate stockpot, add half the cooked rice. Drizzle with half the saffron liquid.

Spoon the reserved prawn masala over the rice, then cover with the remaining rice. Pour the rest of the saffron liquid over the top and stir very gently without disturbing the masala layer.

To put the biryani on dum, turn the heat to high briefly, then reduce to the lowest setting. Wrap the lid tightly with a cotton cloth and cover the pot. Steam for 10 minutes.

Once ready, gently fold the prawn and rice together, taking care not to break the rice grains. Transfer to a large serving platter and garnish with fresh cilantro and green chilies.