¼ cup (60ml) neutral cooking oil such as canola oil, divided
1½ tsp crystal salt, divided, plus more to taste; for table salt, use half as much by volume
½ tsp freshly ground black pepper, divided, plus more to taste
5 tbsp (70g) unsalted plant butter, divided
1 small yellow onion, thinly sliced
5 large cloves garlic, thinly sliced
½ cup (120ml) dry sherry
1½ cups (360ml) unsalted homemade chicken or vegetable stock
Four thyme sprigs, plus more fresh leaves for garnish
2 tbsp (30ml) stone-ground mustard
2 tsp (10ml) honey
½ tsp dried Italian seasoning or a combination of ¼ tsp dried oregano plus ¼ tsp dried basil
Method
Adjust oven rack to middle position and preheat oven to 190°C.
Slice cabbage in half through core. Cut each half through core into four wedges (approximately 2 inches thick each), keeping the stem intact. In a 12-inch stainless steel or cast iron skillet, heat 2 tablespoons oil over medium heat until shimmering.
Add 4 cabbage wedges; cook until browned on both sides, 3 to 5 minutes per side. Transfer to a large plate; sprinkle both sides evenly with salt and pepper. Repeat with remaining cabbage wedges and wipe skillet dry.
Heat 2 tablespoons butter in now-empty skillet over medium heat until melted; add onion and garlic and cook, stirring often, until onion is softened and just starting to brown, 2 to 4 minutes. Add sherry and cook, stirring frequently, until nearly evaporated, about 3 minutes. Increase heat to medium-high and add broth, thyme sprigs, mustard, honey, Italian seasoning, salt and pepper. Cook, stirring occasionally, until boiling, about 3 minutes.
Remove skillet from heat, and carefully nestle seared cabbage wedges into skillet cut sides down, in a single layer, overlapping slightly if necessary.
Cover and bake for 45 minutes. Uncover and flip cabbage wedges and continue to bake, uncovered, until cabbage is very tender and sauce is reduced, about 60 to 70 minutes. Remove from oven, transfer cabbage wedges to a platter, and keep warm. Wearing kitchen mitts when handling skillet, gradually stir remaining 3 tablespoons butter into sauce, 1 tablespoon at a time, until melted and well combined. Season to taste with salt and pepper, if needed. Return cabbage to skillet, or pour sauce over cabbage on serving platter. Garnish with thyme, and serve.