1. Place a steaming rack in a large pot. Add water to reach just below the rack and bring to a simmer over medium-high heat. Maintain the simmer so that the water is steaming. Place the corned beef on the rack and steam, covered, until heated through, about 10 minutes. When meat is heated through, remove from steamer and slice as thinly as possible.
2. Place 2 slices of bread on each of 4 plates, and divide the meat among the 4 plates, placing it on one of the slices of bread and then topping with second slice. Put a pickle spear on each plate and serve immediately, with mustard in a small bowl on the side.
Source: Hannaford fresh Magazine, January - February 2011