Preheat the oven to 400 °F
Crisp the Pastrami: In a large oven-safe skillet over medium heat, add olive oil and cook the diced pastrami (or corned beef) until browned and slightly crisp. Remove with a slotted spoon and set aside, leaving some fat in the pan.
Sauté the Green Beans: Add a splash more olive oil if needed, and increase the heat to medium-high. Then, add the green beans with a pinch of salt to the same skillet and sauté until bright green and lightly blistered, about 5-7 minutes. While the green beans cook, prepare the sauce. (See notes for tips to make restaurant-style green beans).
Make the Sauce: In a small bowl, whisk together chicken broth, Worcestershire sauce, Dijon mustard, ketchup, vinegar, honey, and celery seed. When the green beans are just tender, pour over and toss to coat. Simmer for 30 seconds to 1 minute to slightly reduce the sauce. Turn off the heat.
Add the Sauerkraut and Pastrami: Stir in the sauerkraut and the crisped pastrami until everything is evenly combined.
Top + Bake: Mix Panko, caraway, and olive oil in a small bowl. Sprinkle the Swiss cheese evenly over the green beans, then sprinkle the Panko mixture over the cheese. Bake for 5-8 minutes, until melted, golden, and bubbly.
Serve hot, optionally topped with chopped parsley.