Preparation

Make the dressing

• In a small mixing bowl, mash the blue cheese with a fork. Add the mayonnaise, Worcestershire sauce, buttermilk, lemon juice, Sriracha, and a pinch of salt and black pepper. Stir to combine. Refrigerate in an airtight container for up to one week.

Make the salad

• Position a rack in the center of the oven and heat the oven to 400°F.
• Lay the pastrami flat on a small foil-lined baking sheet and roast until crisp, 10 to 15 minutes. Transfer to a paper-towel-lined plate, cool, then tear or crumble.
• Cut the cabbage into 4 wedges through the root end, leaving some of the core intact on each piece so the wedges don’t fall apart. On a large foil-lined rimmed baking sheet, coat the cabbage wedges with the oil, and season lightly with salt and pepper. Put the wedges on a flat side and roast until browned on the bottom, about 20 minutes. (Don’t worry if the outer leaves begin to burn.) Flip each wedge and continue roasting until the second side is browned as well, about 10 minutes longer. Remove from the oven and let cool. Trim and discard any tough cores from the cooled wedges as well as any overly charred leaves.
• Spread about 1 Tbs. of the blue cheese dressing on each of four serving plates. Place one of the cooled cabbage wedges on top and drizzle with more of the remaining dressing. Scatter the pastrami over the wedges and garnish with the tomatoes. Season with salt and pepper, sprinkle with the chives, and serve.