Tblisi Beef

Combine black pepper, white pepper, red pepper flakes, salt, peppercorns, dry mustard, paprika, and allspice in a small bowl to create the spice blend.

Pat the beef steaks dry with paper towels and cut them into bite-sized pieces, approximately 1-1.5 inches.

Heat the vegetable oil in a large, heavy-bottomed pot or Dutch oven over medium-high heat until shimmering.

Generously coat the beef pieces with the spice blend, then working in batches to avoid crowding, sear the beef until deeply browned on all sides.

Remove the seared beef and set aside; reduce heat to medium and add the chopped onions to the pot, stirring frequently until they become soft and translucent.

Slice the mushroom and add it to the pot with the onions, stirring to combine and cook for 2-3 minutes.

Return the beef to the pot and add the beef stock, stirring well to incorporate the fond from the bottom of the pot.

Bring the mixture to a boil, then reduce heat to medium-low and simmer, covered, until the beef is tender and the flavors have melded, approximately 30-35 minutes.

Meanwhile, bring a large pot of salted water to a boil and cook the flat noodles according to package directions until al dente, then drain and set aside.

Remove the beef stew from heat and stir in the sour cream or plain yogurt until fully incorporated and the sauce is creamy.

Divide the cooked noodles among four serving bowls and ladle the Tbilisi beef and sauce generously over the top; serve immediately while hot.