In a small bowl, add one teaspoon lemon juice and a pinch of salt to the ginger strips and keep in the refrigerator till use. Heat sufficient oil on a thick tawa till medium hot.
Place the potato pieces and shallow-fry till crisp and golden. Drain and place on an absorbent paper. In the same oil add sweet potato pieces and shallow-fry till crisp and golden. Drain and place on an absorbent paper.
Transfer the potatoes and sweet potatoes into a big bowl. Add salt, sweet date and tamarind chutney, chaat masala, red chilli powder, cumin powder, green chilies, coriander leaves and the remaining lemon juice and mix well.
To serve transfer the mixture into a serving bowl, garnish with ginger strips and serve immediately.