Pan-Roasted Trout with Walnut-Green Sauce

Boned and butterflied whole rainbow trout head and, small

Baby spinach

Greens such as watercress, spicy mixed

Herbs such as chives, mixed fresh

Lemon juice plus lemon, freshly squeezed slices

Dijon mustard

Kosher salt and freshly ground black pepper

Walnut or olive oil

Walnut, toasted halves

Buttermilk

Greek yogurt, plain