Cut the frozen cassava into equal pieces, lengthwise (like fries).
In a deep pan add enough oil to deep fry the cassava. Heat the oil on medium heat. Test the oil to see if it is hot enough, by adding a small piece of cassava. If it floats, the oil is ready to use.
Carefully add the cassava chips, making sure that the pot is not crowded. Cook for a couple of minutes on each side and flip and once light golden.
Remove from the oil using a strainer or a slotted spoon to drain the oil. Transfer to a plate lined with paper towel to remove excess oil.
Repeat to fry the rest of the cassava.
Toss with salt, chilli powder, chaat masala and/or lemon juice. Serve hot.