- 2 lemons
- Four 8- to -10ounce whole rainbow trout, cleaned (see Notes, or ask the fishmonger to perform this task)
- 2 teaspoons extra-virgin olive oil
- Kosher salt, to taste
- Freshly milled black pepper, to taste
- 4 small garlic cloves, very thinly sliced
- 1 small bunch fresh thyme
- 2 tablespoons unsalted butter, cubed
- 2 tablespoons capers, rinsed and patted dry
- Prepare a high-heat fire, with the flames licking the grill grate. Let it burn steadily for 30 minutes.
- Slice 1 lemon very thinly; cut the remaining lemon into wedges.
- Coat the outside of the fish with oil. Season the fish all over, inside and out, with salt and pepper. Stuff each fish with lemon slices, garlic slices, and thyme. Top with butter cubes and capers.
- Heat a cast-iron skillet over the grill grate until very hot. Carefully arrange the stuffed trout in the skillet and cook until the skin is crisp-golden and the flesh is opaque and flakes easily with a fork, 4 to 5 minutes per side.
- Serve hot, with lemon wedges for squeezing over the fish.