For this traditional confit (the analog alternative to our more modern and streamlined sous vide duck confit recipe, we start by curing duck legs for 24 hours with salt, black pepper, and an allium cure made with shallots, onion, garlic, parsley, and thyme.
Massage bag until duck legs are evenly coated on all sides. Lay bag flat on rimmed baking sheet and refrigerate for at least 24 hours and up to 48 hours. When Ready to Cook: Adjust oven rack to middle position and preheat oven to 225°F (105°C).
Serve the duck with rutabaga and the balsamic sauce. If you don't have a slow cooker, you could use a dutch oven and cook it on the stove on medium-high heat. It'll take about 2-3 hours, depending on the size of the thighs. You could also cook it in the oven at 260 °F (125 °C) after step 2.
Pour off the duck fat. Brush a grill pan with some of the used duck fat and heat over medium-high heat until smoking. Add baked duck; cook in batches until skin is crispy, about 90 seconds per side. Regular white sugar can be substituted for the cane sugar.