Heat oven 400°F.

Cook salami in a skillet until almost brown.

Add onion and potato, 1 Tbsp. olive oil, salt, pepper and cook until potatoes are brown.

Whisk egg and cheese and pour into skillet stirring to combine ingredients.

Transfer to oven and bake until puffy and brown around the edges.

In a medium bowl whisk together the vinegar, mustard, remaining oil, salt, pepper and serve with egg bake.