How to Make It
Light a grill. Preheat the oven to 500°. 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.
One Serving 401 cal, 16 gm fat, 2.5 gm sat fat, 30 gm carb, 5 gm fiber.