* Preheat a charcoal or gas grill until red hot.
* Using a sharp knife, cut into the salmon lengthwise starting at the thickest end, working your way ¾ of the way through—do not cut the filet in half. The idea is to cut an “opening” into the filet but not separate the filet into two.
* In a small bowl, mix the goat cheese, salt, pepper and herbs until smooth.
* Lift the top of the salmon filet up and spread the goat cheese on top of the bottom layer. Top with the spinach leaves, and sprinkle with salt and pepper. Place the top filet back on and press down so the stuffing is patted down. Place the salmon onto a thick piece of aluminum foil.
* Cut the lemon in half. Cut half the lemon into paper thin slices. Squeeze the remaining lemon half on top of the salmon. Place the lemon slices on top of the fish. Drizzle the oil on top of the fish, sprinkle with a grinding of pepper, and seal tightly.
* Place the salmon on the hot grill and cook for about 15 to 20 minutes, depending on the thickness of the fish. The salmon should just begin to flake. Serves 4 to 6.