Heat a pan over medium heat. Add cumin seeds, onion, and oil (optional). Sauté until golden brown, approximately 5 to 7 minutes. Sprinkle water as needed to prevent mixture from sticking to pan.
In the meantime, wash urad daal with water a few times. then set aside.
Once onions are ready, add water, urad daal, ginger, garlic, jalapeño, coriander powder, crushed red pepper flakes, cumin powder, turmeric powder and salt. Mix together well.
Bring the mixture to boil, then reduce heat to low-medium. Half cover with lid and allow the daal maash to continue cooking until the remaining water dissolves, which is usually about 20 to 25 minutes.
Add garnishes and serve hot!