Cook dal in pressure cooker until re-hydrated and soft, 6–10 minutes.
Heat oil in a heavy frying pan. Add black mustard seed and cook until popped. Be careful not to burn oil and keep a cover close by because they can pop out of the pan. Add garlic, onions, ginger, and pepper, cooking until browned. Stir in dal and curry powder, adding water as needed. Cook until dal is tender.