Preparation

• Remove the stems from the kale and discard. Slice the leaves crosswise into 1/2-inch strips. Wash and dry the kale well and then pile into two large zip-top freezer bags. Gently press out as much air as possible, seal, and freeze.
• Heat the oil in a 12-inch skillet over medium-low heat, add the pancetta, and cook, stirring occasionally, until it just starts to brown, 4 to 6 minutes. Add the garlic and red pepper flakes and cook, stirring, until fragrant, about 30 seconds more. Let cool in the pan (the pancetta will not be crisp). Scrape everything, including the fat, into a zip-top freezer bag or other airtight container and freeze.

To finish the dish

• Two hours before serving: Take the kale and pancetta mixture out of the freezer and let thaw at room temperature.
• Heat the pancetta mixture in a wide 5- to 6-quart pot over medium-low heat until the fat melts and the pancetta is crisp, about 3 minutes. Drain the pancetta mixture in a fine-mesh sieve set over a heatproof bowl. Wipe out the pot with paper towels.
• Return 3 Tbs. of the fat to the pot and heat over medium-high heat until shimmering hot. Add a big handful of the kale and toss with tongs until it’s coated with the fat, about 20 seconds. Continue adding the kale by the handful and tossing to coat. When all of the kale is in the pot, add 1/2 cup water, season with 1/2 tsp. salt, and cover. Reduce the heat to medium, cook for 4 minutes, and then remove the lid. Toss and continue cooking until the kale is tender, up to another 8 minutes depending on the variety. If the pan is dry before the kale is fully tender, add a little water.
• Add the lemon juice, toss, and season to taste with salt and a little more juice, if necessary. Toss half of the pancetta with the kale, pile into a bowl, and top with the remaining pancetta. Serve.

Make Ahead Tips

The kale and cooked pancetta can be frozen for up to two weeks.