How to Make It
Preheat the oven to 375°. Lightly brush one side of each slice of bread with the olive oil and sprinkle with the Parmesan. Bake for about 10 minutes, or until lightly browned.
Spread the walnuts in a small pan and bake for 4 to 5 minutes, or until fragrant and lightly toasted. In a small bowl, whisk the oil with 1/4 cup of the vinegar, the mustard and 1/2 teaspoon each of salt and pepper. Stir in the currants and set the dressing aside.
Quarter and core the apple; thinly slice the quarters crosswise. Toss the apple with the remaining 1 teaspoon vinegar to prevent discoloring.
In a large bowl, toss together the cabbage, ham, onion, apple and caraway seeds. Whisk the dressing, then pour it over the salad and toss thoroughly. Serve at once on large plates, with the Parmesan croûtes on the side.