1. Pickle the onions first: toss the sliced red onion with lemon juice or vinegar, sugar, and salt. Set aside at least 15 minutes. They will turn bright pink.
2. Make the raita: stir the grated cucumber, cumin, and salt into the yogurt. Keep it thick, not runny, or the burrito will get soggy.
3. Heat the Truly Indian Bombay Biryani per pack instructions.
4. Warm the tortilla so it is pliable and will not crack when rolled.
5. Layer down the center: biryani first, then a spoon of raita, then the pickled onions and cilantro. Do not overfill.
6. Fold in the sides and roll tight into a burrito.
7. Sear seam side down in a hot pan with a little oil or butter until golden and crisp on both sides. Slice on the diagonal to show the cross section.