Heat the oven to 400ºF.

• Rinse the cabbage, pat dry and cut into thin slices.
• Cut the cucumbers in half lengthwise and then into ¼-inch-thick pieces.
• Rinse the radishes, cut in half and thinly slice.
• Peel the ginger and finely chop or grate.
• Finely chop the cilantro, including the stems.
• Juice the limes.
• Tear the kaffir lime leaves into pieces.

On a sheet pan, spread the cashews and roast in the oven until lightly toasted, 5 to 7 minutes.

Layer two banana leaves on top of each other for each fillet of fish. Scatter the chopped ginger and kaffir lime leaves evenly between two sets of leaves. Top with the salmon fillets and drizzle with oil. Wrap each fillet by folding the short ends of the banana leaves into each other. Then fold in the bottom edge and flip over the other end to seal. Place in a baking pan, seam side down. Add ¼ cup water to the pan and roast in the oven until the salmon is flaky and opaque, 18 to 20 minutes. While the salmon cooks, make the salad.

In a small bowl, combine 2 tablespoons lime juice with the fish sauce dressing and remaining ginger.
In a mixing bowl, combine the cabbage, cucumbers, radish, cilantro and toasted cashews. Add 1 to 2 tablespoons oil, half of the dressing and toss until well combined.

Transfer the banana leaf-wrapped salmon to individual plates. Carefully unwrap, taking care not to lose the liquid collected in the leaves. Serve the salmon in the leaves with the slaw on the side.