1/2 c. unbleached all-purpose flour
3/4 tsp. salt
1/2 tsp. freshly ground pepper
4 med. trout, cleaned and scaled
6 tbsp. (3/4 stick) unsalted butter
1/2 c. chopped, husked toasted hazelnuts (about 2 ounces)
3 green onions, sliced
2/3 c. whipping cream, boiled until reduced to 1/3 c.
1 1/2 tbsp. fresh lemon juice
1/4 tsp. salt
1/4 tsp. freshly ground pepper

Prepare barbecue (high heat). Combine flour, 3/4 teaspoon salt, and 1/2 teaspoon pepper on large plate. Dredge trout in flour mixture; shake off excess.

In heavy, large cast-iron skillet, set on grill; melt 3 tablespoons butter until foaming. Add trout. Cover trout with grill lid or heavy-duty foil and cook 4 minutes. Carefully turn trout. Cook until flesh is opaque but still moist, about 4 minutes. Transfer trout to platter. Tent with foil to keep warm.

Wipe out skillet. Melt remaining 3 tablespoons butter in skillet on grill. Add hazelnuts and green onions and cook until onions wilt, stirring occasionally, about 3 minutes. Add reduced cream and stir until heated through. Mix in lemon juice, 1/4 teaspoon salt, and pepper. Spoon sauce over trout.