1. Trim the Brussels spouts and discard any damaged outside leaves. Fit a food processor with the slicing blade. Force the sprouts, a few at a time, through the chute with the blade in motion. You should have about 8 cups of shredded sprouts.
2. Heat the vegetable oil in a large skillet over medium-high heat. Add the pancetta and cook, stirring often, until very lightly browned, 3 to 5 minutes. Add the sprouts and cook, stirring, until tender, about 5 minutes. Pour in the lemon juice and increase the heat to high.
3. Season with salt and pepper, and stir until the Brussels spouts are tender. Empty into a warmed serving bowl and top with the cheese.