Arrange dill fronds on a sheet pan. Rinse cavity of fish, pat dry and lay over dill, skin side down. Sprinkle the trout’s flesh with sea salt and lemon zest and brush with melted butter. Let fish stand for 5 to 10 minutes. Using apple wood staves, build a medium fire in the grill and burn down for 15 to 20 minutes. Squeeze ½ lemon over fish. Transfer dill fronds to grilling surface and top with fish, skin side down. Roast fish, basting periodically with melted butter, for 15 to 20 minutes, or until flesh just begins to flake. Transfer fish and dill fronds to large platter, and season to taste with salt. Squeeze second half of lemon over flesh, garnish with minced dill and serve immediately.