Position the racks in the upper and lower thirds of the oven. Use a pastry brush to lightly grease 2 large rimmed baking sheets with olive oil.

Bring a large pot of water to a boil over high heat. While you wait for the water to boil, trim the very bottoms from the brussels sprouts and remove any yellowed leaves.

When the water reaches a boil, add the brussels sprouts. Boil until just tender, 5 to 6 minutes. (To test, remove a sprout from the water, lay it on a cutting board, and see if you can smash it with the bottom of a drinking glass.) Once they’re ready, drain the brussels sprouts. Let them sit for 1 to 2 minutes to allow the steam to evaporate.

Divide the brussels sprouts between the greased baking sheets, spacing them evenly apart. Using the bottom of a sturdy drinking glass, smash each one down so it’s less than ½-inch thick. Don’t worry if some leaves fall off or a few of the brussels sprouts fall apart.

In a small bowl, mix together the salt, pepper, and lemon zest. Use the pastry brush to brush the tops of the sprouts evenly with the oil, then sprinkle evenly with half of the salt mixture.

Put the baking sheets in the oven and roast for 15 minutes, rotating the pans from top to bottom halfway through.

Remove the pans from the oven. Using a metal spatula, flip each brussels sprout (this is easier if you let the pans sit for a minute; the sprouts will naturally loosen from the pans). Sprinkle evenly with the remaining seasoning. Return the pans to the oven and roast until the bottoms of the sprouts are deeply browned, another 5 to 8 minutes.

Drizzle the lemon juice all over the brussels sprouts and serve immediately. Refrigerate leftovers in an airtight container for up to 3 days.