Preheat oven to 450 degrees. Thinly slice the mushrooms. Cut the bread into 1/2-inch cubes. Cut half the lemon into rounds. Season the sole on all sides with salt and pepper.

Cook the vegetables: heat 1 tablespoon oil in a large pan over medium-high heat. Add the mushrooms to the pan and cook, tossing, until soft and golden brown, 4-5 minutes. Season with salt and pepper and set aside. Add the green beans and 1/3 cup water to the same pan over medium heat. Cook, tossing, for 6-7 minutes, until green beans are tender and water has evaporated. Season with salt and pepper.

Assemble each foil packet: fold an 18-inch piece of tin foil in half widthwise, then open it up like a book. In the center of one side, layer half the vegetables, 1 sole fillet, a pinch of salt and pepper, and a lemon round. Optional: finish with a drizzle of olive oil for an indulgent twist. Fold over the tin foil and crimp to seal the edges around the fish. Repeat.

Place the foil packets on a baking sheet and place in the oven for 9-12 minutes, until fish is flaky and opaque.

Make the croutons: while the fish cooks, heat 1 tablespoon butter over medium heat in the same pan you cooked the mushrooms in. Add the cubed bread and cook, tossing, until golden brown and crispy, 3-4 minutes. Season with salt and pepper and set aside.

Make the brown-butter caper sauce: heat 2 tablespoons butter over medium-low heat in the same pan you cooked the croutons in. Cook, watching carefully, until the butter foams and solids turn golden brown. You’ll see little golden brown specks beginning to develop in the bottom of the pan. Immediately remove from heat and stir in the capers and a squeeze of lemon. Taste and season with salt and pepper, if necessary.

Plate the contents of the foil packets and drizzle with the brown-butter caper sauce. Sprinkle with the croutons and enjoy!