Properly browning onions for biryani, achieving a deep golden-brown color without burning, typically takes between 25-40 minutes over medium-low heat, requiring constant stirring.
Browning onions for biryani, also known as 'birista,' is a crucial step that imparts a sweet, caramelized flavor and rich color to the dish. The process involves slowly cooking thinly sliced onions in oil over medium-low heat. The initial stage involves the onions softening and becoming translucent, which takes about 10-15 minutes. As the moisture evaporates, the onions will start to turn light golden. This is where constant attention is needed. The color will deepen gradually, transitioning from golden to a rich, deep brown. This final browning stage can take another 15-25 minutes. The key is to stir frequently to ensure even browning and prevent burning. Burnt onions will impart a bitter taste, ruining the biryani. The total time depends on the type of onion, the thickness of the slices, and the heat of your stove.
To prevent onions from burning, add a pinch of salt at the beginning of the cooking process. Salt helps draw out moisture, which aids in even browning and prevents sticking. Also, avoid overcrowding the pan; cook the onions in batches if necessary.