- 1 pound fingerling potatoes, scrubbed
- 1/2 pound assorted mushrooms (brown, oyster, portobello), thinly sliced
- 4 teaspoons tamari
- 4 teaspoons aged balsamic vinegar
- 3 tablespoons extra-virgin olive oil
- Salt and freshly ground pepper
- 4 striped bass fillets, skinned
- 2 teaspoons chopped rosemary
- 4 round purple plums, halved and pitted
- Watercress sprigs, for garnish
- Light a grill. Preheat the oven to 500 degrees F. In a medium saucepan of boiling, salted water, cook the potatoes until tender, about 10 minutes. Drain and let cool. Peel the potatoes and halve them lengthwise.
- Tear off four 20-by-14-inch sheets of parchment or foil. Spread equal amounts of potatoes and mushrooms on half of each sheet. In a small bowl, mix the tamari with the vinegar and 1 tablespoon of olive oil. Drizzle over the potatoes and mushrooms and season with salt and pepper. Fold the sheets over the vegetables and crimp to seal, if using parchment; if using foil, fold in the edges to seal the packages. Transfer the papillotes to 2 baking sheets and bake for about 15 minutes, or until sizzling.
- Drizzle the bass fillets with 1 1/2 tablespoons of the olive oil, sprinkle with the rosemary and season with salt and pepper. Drizzle the plums with the remaining 1/2 tablespoon of olive oil. Grill the bass over high heat until nicely charred and just cooked, 3 to 4 minutes per side. Grill the plums, cut side down, until lightly charred, about 2 minutes per side.
- Transfer the bass fillets and plums to plates. Set a papillote on each plate and open it, pouring out the potatoes, mushrooms and any juices. Watch out for the hot steam. Serve garnished with watercress.