
Turn store-bought corned beef into tender, peppery homemade pastrami with a bold spice crust and no smoker required. Slow cooking makes the meat juicy, while a final oven roast sets the crust for deli-style slices perfect for rye sandwiches.
In a bowl, combine the black pepper, coriander powder, mustard powder, brown sugar, smoked paprika, garlic powder, and onion powder. Pat the corned beef very dry, then press the spice mixture firmly over every side. Drizzle or brush with liquid smoke, if using.
Place the beef fat-side down on a large sheet of foil and wrap it tightly. Wrap it again in a second sheet of foil, then turn it over so the fat cap faces up.
Set a rack or trivet inside the slow cooker and place the wrapped beef on top. Cook on low for about 10 hours, until very tender. For an electric pressure cooker, place the beef on a trivet with 1 cup water underneath and cook on high pressure for 1 hour 40 minutes, then let the pressure release naturally.
Remove the beef carefully and let it cool. Save any cooking juices from the foil or cooker. Refrigerate the wrapped beef for at least 6 hours, or overnight, so it firms up for cleaner slicing.
Heat the oven to 350°F. Unwrap the chilled beef and place it on a rack set over a baking tray. Bake for about 30 minutes, until the spice crust is dry, fragrant, and set.
Let the pastrami rest briefly, then slice it thinly across the grain. To reheat, place slices in a shallow dish with a spoonful of reserved juices, cover, and microwave or warm gently until hot.
For a New York deli-style sandwich, pile warm pastrami onto toasted rye bread with plenty of mustard. Serve with pickles and plain potato chips.
For a Reuben-style sandwich, layer warm pastrami with Swiss cheese, sauerkraut, and dressing on rye bread, then toast until the bread is crisp and the cheese melts.
If your corned beef is very salty, soak it in cold water for 1-2 hours, changing the water once, then dry it thoroughly before seasoning. Chilling before slicing is important; warm pastrami can shred instead of slicing cleanly. Store sliced pastrami with a little reserved cooking juice in an airtight container for up to 4 days, or freeze for up to 2 months.
