2 cups walnut halves
1 small head red cabbage (about 2 pounds)
3/4 cup apple cider vinegar
1 clove garlic, minced
2 sprigs thyme
1/4 cup Dijon mustard
Freshly ground white pepper
2/3 cup grapeseed oil
4 Belgian endives
2 Granny Smith apples
4 ounces Gruyère cheese, cut into matchsticks
Preheat oven to 325°F. Place the walnuts on a baking sheet and bake until golden brown, about 5 minutes. When cool, crumble in your hands to break them up.
Quarter and core the red cabbage. Finely slice the leaves to ?-inch thickness and transfer to a large bowl. In a small saucepan, combine ½ cup of the apple cider vinegar with the garlic, thyme sprigs and a pinch of salt. Bring to a simmer, and then pour over the cabbage. Toss to combine, cover and set aside to marinate for at least 1 hour and up to 8 hours.
In a small bowl, whisk the remaining ¼ cup vinegar with the mustard and a pinch each of salt and white pepper. Slowly whisk in the grapeseed oil to emulsify.
Remove the leaves from the endives. Discard the cores. Thinly slice the leaves from three heads lengthwise to ?-inch thickness. Cut the apples into matchsticks.
Just before serving, strain excess liquid from the marinated cabbage. Toss in the endive, apples and Gruyère. Add just enough of the mustard dressing to coat. Season to taste with salt and pepper. Serve topped with crumbled walnuts and garnish with remaining whole endive leaves.