In a small bowl, combine sour cream, relish, ketchup, 1 teaspoon Worcestershire sauce, salt and pepper. Set aside.

Place sauerkraut in a small pot and warm through.

Combine beef with remaining 2 teaspoons Worcestershire, grated onion, salt and pepper. Form 4 thin patties.

Lightly toast bagels.

Heat pastrami in a skillet, folding 2 slices together, until brown and crisp on each side; remove to plate.

Heat a cast-iron skillet over medium-high heat with a drizzle of oil to coat pan lightly. Add patties and brown 6 minutes, turning occasionally. Top patties with hot pastrami, sauerkraut and cheese, and loosely cover with foil to melt cheese.

Slather bagel bottoms with mustard, add patties and top with Russian dressing and pastrami. Place bagel tops in place, cut and serve with deli pickles, chips and slaw alongside. Pass extra dressing and mustard at the table.