Corned Beef And Coleslaw Sandwich

2 tablespoons of white-wine vinegar
1 1/2 tablespoons of  Dijon-style mustard + spreading on the bread
1 1/2 tablespoons of drained bottled horseradish
1/4 cup of Olive oil
3 cups of thinly sliced cabbage
1 cup of thinly sliced red onion
1 cup of coarsely grated carrots
a 16-inch-long loaf of Italian or French bread, halved horizontally with a serrated  knife
1/2 pound of thinly sliced corned beef

In a large bowl whisk together the vinegar, 1 1/2 tablespoons of the mustard, the horseradish, and salt and pepper to taste, add the oil in a stream, whisking, and whisk the dressing until it is emulsified. Add the cabbage, the onion, and the carrots, toss the coleslaw well, and chill it, covered, overnight. Spread the bread with the additional mustard, arrange the coleslaw and the corned beef on the bottom half of the bread, and fit the top half on the filled bottom, pressing the loaf together firmly. Quarter the sandwich with a serrated knife and wrap it tightly in plastic wrap. (The sandwich may be made 6 hours in advance and kept wrapped and chilled). Serves 4. Gourmet August 1993