Ingredients

For pickled apples
2 red apples such as Gala or Idared
1/2 cup cider vinegar
1 cup water
1/2 cup sugar
1 teaspoon salt
1 teaspoon pickling spice

1/2 cup walnut halves (3 ounces)
1/4 cup olive oil
1 bunch collard greens (1 pound)
1/2 teaspoon kosher salt

Instructions

Make pickled apples:
Quarter and core apples, then cut each quarter lengthwise into 1/8-inch-thick slices. Boil vinegar, water, sugar, salt, and pickling spice in a saucepan, stirring, until sugar is dissolved. Add apples and return to a boil. Transfer to a heatproof bowl and cool. Chill, uncovered, until cold, about 1 hour.

Prepare nuts while apples chill:
Toast walnuts in oil in a small skillet over moderate heat, stirring occasionally, until a shade darker. Cool nuts in oil. Transfer nuts to a cutting board with a slotted spoon, reserving oil. Coarsely chop 1 tablespoon nuts and finely chop remaining nuts.

Prepare collard greens:
Halve each collard leaf lengthwise with kitchen shears or a sharp knife, cutting out and discarding center ribs. Stack leaves and cut crosswise into 1/4-inch-wide strips. Transfer to a large bowl.

Just before serving:
Transfer all nuts and oil from skillet to collards and toss with 1/2 teaspoon salt and pepper to taste. Add apple slices, discarding pickling liquid and spices, and toss again.