What ingredient is found in both millionaires cut and pepercorn steak?

The ingredient found in both millionaires cut and peppercorn steak is dairy. In the context of these dishes, dairy products are often used to enhance flavors and textures. For instance, in millionaires cut, which is a premium steak offering, various cream-based sauces or butters may be employed to add richness. Similarly, the peppercorn steak often incorporates a cream sauce that complements the spiciness of the peppercorns, creating a well-balanced flavor profile.

While other options like seafood, mustard, and egg may appear in various dishes, they do not consistently feature in both millionaires cut and peppercorn steak. Therefore, the presence of dairy is a commonality that defines these two specific dishes.