Heat the olive oil in the heavy bottomed pot over medium-high heat and add the popcorn kernels. When the popcorns starts to pop, cover the pot tightly and continue to cook until all the popcorn pops, about 2 to 3 minutes, shaking the pot occasionally. Pour the popcorn into the large bowl.
While the popcorn pops, melt the butter in the sauté pan over medium-high heat until it is brown, shaking the pan occasionally. Remove the pan from the heat. Add the rosemary to the butter and let it sit for a minute or two to infuse the butter with flavor, then pour the butter mixture over the popcorn. Toss well. Add the salt and pepper and lemon zest and toss well.
Equipment4-quart heavy bottom pan with lid medium sauté pan large bowl