Add the oil to a medium-sized pan with two handles. Heat over medium-high heat, stirring occasionally, until the oil is hot. It shouldn't be smoking though, so keep an eye on it.
Throw in the garam masala and popcorn kernels, stir them around with a wooden spoon to coat with the garam masala, then cover with a lid.
Put on some oven mitts, grab the handles of the pan and gently start sliding the pan back and forth over the stove, making sure the lid doesn't fly off in the process. After about a minute or so, the first kernel will pop. Keep sliding the pan over the heat (lifting and shaking the pan every now) until all of the kernels have popped. When the popping slows down (to about 1 pop every 2 seconds) take the pan off the heat. Serve immediately!
Recipe by The Tough Cookie at https://thetoughcookie.com/2014/01/03/healthy-garam-masala-popcorn/