INGREDIENTS
1
green cabbage, thinly sliced (4 cups)
2 tbsp
cider vinegar
1 tbsp
sugar
1/2 tsp
kosher salt
4
4-by-6-inch pieces of focaccia, split
1/4 cup
ketchup
1/4 cup
mayonnaise
8
1/4-inch-thick slices of Gruyère cheese (4 ounces)
1/2 lb
thinly sliced corned beef
2 tbsp
unsalted butter, softened