In a small bowl, stir together the garam masala, smoked paprika, salt and pepper and set aside.
Using a mandoline or a sharp knife, slice the plantains into very thin slices, about 1/8-inch thickness.
Pour the oil into a large, heavy bottomed pot and heat it to 350 degrees F. The oil level should come one-third of the way up the sides of the pot. If there is too much oil, it will overflow when the chips are added. Alternatively, use a deep-fryer.
Fry the plantain slices in batches in the hot oil until crispy and golden, 2 to 3 minutes. Stir them a bit while they fry to prevent them from sticking together. Remove the plantains and drain on a paper towel-lined baking sheet. Sprinkle with the spice mixture and serve.
Alternatively, the plantain chips can be cooled and stored in an airtight container for up to 10 days.