Clean and soak both the dhals overnight in water. Next morning wash well, and drain off all the liquid. Chop green chillies and ginger. Grate the cucumber and squeeze out the juice.
Just before serving, mix the dhals, green chillies, ginger, cucumber, salt and coconut. Heat oil, add mustard, urrad dhal, red chillies and hing. When mustard splutters pour into the salad, squueze lime juice into it and if liked, add chopped coriander leaves to it. This is a traditional salad and is very nutritious.