Beef with grain

1 tbsp vegetable oil 2 small potatoes , diced 1/2 lb corned beef , thinly sliced across grain 1 tsp spices that come with corned beef 1/2 tsp red pepper flake[...]

1/4 cup whole grain Dijon mustard 1/4 cup low-fat mayonnaise 6 ciabatta rolls or mini baguettes, split horizontally 6 1/4-inch-thick slices rare roast beef[...]