Step 1
In a large pot, bring the broth to a boil. Add the bucatini and salt, and cook, stirring every minute or two, for 6–8 minutes (or according to the package directions).
Step 2
Meanwhile, to a small skillet over medium-high heat, add the oil. When hot, add the Dijon mustard, coriander, fennel seeds, mustard seeds, onion powder, and paprika. Cook, stirring occasionally, until fragrant, 3 minutes. Remove from the heat. Stir in the pastrami and sauerkraut.
Step 3
Drain the bucatini, reserving a few tablespoons of broth. Add the bucatini back to the pot and stir in the pastrami mixture. Add a tablespoon of broth at a time as needed if it looks dry. Season to taste with salt, and serve hot.