Wash the bananas and pat them dry with a tissue paper. Score the banana skin from top to bottom, along the ridges. This helps to peel the banana easily.
Cut the banana into thin slices, using a slicer or knife. (If you are using a slicer, keep 2-3 tbsp of oil in a small bowl and dip the tip of the banana in the oil after 2-3 slice. This helps you to slice the banana easily and also keeps the slices separate). Separate the slices and keep aside.
Heat oil in a deep and wide pan for deep frying. Heat the oil on medium - high flame. To test whether the oil has reached the correct temperature, add a single slice. If the oil starts bubbling and the slice pops to the top immediately, the oil is ready.
Reduce the temperature to low and add the sliced bananas. Make sure the pieces are not sticking together and also the pan is not crowded. Once you add enough slices for a batch, increase the flame to medium - high. Gently stir the chips using a slotted spoon. Cook for 2-4 mins (refer notes). Once the chips are almost crisp, you can hear a crackling sound. Add 1 - 1.5 tsp of salt mixture to the chips. Be careful while adding this, since oil bubbles up a lot. Once the bubbling sound, settles down, cook for a min or so and start removing the chips using a slotted spoon. Drain the chips on paper towel.
Follow the same procedure with the remaining batches. Once the chips cool completely, store it in an airtight container. It can be stored for 2-3 weeks.