That was homemade sauce, Charles. I admit that I wimped a bit and started with ketchup (usually just start with tomato paste), so I added a bit of tomato juice to cut the sweetness (I've also used Bloody Mary mix in the past, but be careful about its high salt content). Then add jarred grated horseradish, Old Bay, wasabi powder, Worcestershire sauce, roasted garlic paste, and gochugiang (Korean fermented bean and chile paste) (Instead of the last 2 items, you can use Sriracha sauce). Mix and let it set for several hours for the flavors to blend.