Purple Potato Gratin with Salmon Mousseline and Beurre Blanc

I bought Peruvian purple fingerling potatoes at the Farmers' market. Purple potatoes have a subtle grainy texture and I thought they'd pair perfectly with salmon mousseline.

Beurre blanc sounds like a sophisticated element in a French dish, but it's really just a white wine butter sauce. It's quite common in France and is often paired with poached fish and steamed vegetables. I think that it complements the crunchy potatoes and velvety salmon mousseline quite well. I finished each dish with a dollop of crème fraîche, some fresh dill and a couple of pink peppercorns. It's a feast for the eyes as well your taste buds.