Corned Beef Sandwich

Method

1. Bring a pan of water to a bare simmer and set a steamer basket or colander over it. Trim the fat cap on the 150 g of corned beef down to a thin layer, then carve the meat across the grain into slices about 3 mm thick.
2. Lay the slices loosely in the steamer, cover and steam for 5 minutes, until the meat is hot all the way through and limp enough to drape over a finger. Do not press it flat — steaming is what keeps deli corned beef juicy rather than dry.
3. Meanwhile, melt the 1 tsp of butter in a dry heavy frying pan over medium heat, if using, and warm the 2 slices slices of rye bread for about 1 minute a side, just until the surface is dry and lightly toasted but the crumb is still soft.