Pat the duck legs dry with paper towels. Mix kosher salt, granulated sugar, and black pepper. Rub the salt mixture evenly over the underside and skin of each leg. Place the smashed garlic, thyme sprigs, and bay leaves between the legs and on top. Put the legs in a shallow container, cover, and refrigerate for 12–24 hours to cure.

Rinse and dry

After curing, remove the duck legs from the refrigerator. Rinse off the cure under cold water to remove excess salt. Pat the legs completely dry with paper towels. Let sit at room temperature for 30 minutes while you preheat the oven to 225°F (110°C).

Slow-cook in duck fat

Place the duck legs in a deep ovenproof dish or a Dutch oven in a single layer. Melt any solid duck fat if necessary and pour enough warm duck fat over the legs to completely submerge them (about 1.5–2 cups). Add the garlic, thyme and bay used during curing into the fat. Cover the dish and place in the preheated oven. Cook gently for 2.5–3 hours until the meat is very tender and easily pulls from the bone.

Cool and store (or crisp before serving)

Remove the dish from the oven and let the legs cool in the fat for 30 minutes. At this point you can refrigerate the legs in the fat for up to 1 week (or freeze). To serve now, remove the legs from the fat, discard excess aromatics, and blot lightly with paper towel. Reserve 2–3 tbs of duck fat for sautéing the cabbage and crisping the skin.

Crisp the skin

Preheat oven to 425°F (220°C) or heat a heavy skillet over medium-high. Place legs skin-side down in a cold skillet using reserved duck fat; cook until skin is deeply golden and crisp, 6–8 minutes. Transfer to a baking sheet and finish in the hot oven 5–7 minutes until skin is fully crisp and internal temperature reaches 160°F (71°C). Rest 5 minutes before serving.

Orange Sauce (Sauce à l'Orange)

Sauté shallot and caramelize sugar

In a small saucepan over medium heat, melt 1 tbs of the butter. Add the minced shallot and cook until soft and translucent, about 2 minutes. Add 2 tbs granulated sugar and cook, stirring, until the sugar lightly caramelizes and takes on an amber color, about 2–3 minutes — watch carefully to avoid burning.

Deglaze and reduce

Carefully add the white wine vinegar to deglaze the pan (it may steam). Stir to dissolve any caramelized sugar bits. Add the orange juice, orange zest, and chicken stock. Bring to a simmer and reduce the liquid until slightly syrupy and reduced by about one-third, about 8–10 minutes.

Finish sauce

Lower the heat to low and whisk in the remaining 2 tbs butter a piece at a time to create a glossy emulsion. If using, stir in the Grand Marnier. If the sauce needs thickening, whisk in the cornstarch slurry a little at a time and simmer 1–2 minutes until the sauce coats the back of a spoon. Season with 1/2 tsp salt and 1/4 tsp black pepper to taste. Keep warm.

Spring Cabbage & Garnish

Prepare cabbage

Core and thinly slice the savoy or spring cabbage. Rinse and spin or pat dry. Slice the spring onions on the bias and segment the orange into supremes if using: cut away peel and pith, then slice between membranes to release segments.

Sauté cabbage

In a large skillet over medium heat, melt 1 tbs butter with 1 tsp olive oil. Add the sliced cabbage and cook, stirring occasionally, until just tender and bright green, about 4–6 minutes. Add the sliced spring onions for the last 1–2 minutes. Season with 1/2 tsp salt and 1/4 tsp black pepper. Toss in the orange segments and toasted nuts just before removing from heat.

Plate and garnish

Place a bed of warm sautéed cabbage on each plate. Set a crisped duck leg atop the cabbage. Spoon the warm orange sauce generously over the duck and a little onto the cabbage. Scatter additional chopped toasted nuts and a few microgreens or extra orange zest for color. Serve immediately.