Preheat the oven to 175°.
Combine the coriander, mint, coconut milk, 2 tablespoons water, 1 tablespoon of the oil, the brown sugar, lime juice, garlic, ginger, pepper and 1/4 teaspoon salt in a food processor. Pulse until smooth, then transfer to a small bowl.
Lay out a 24-inch piece of foil on a baking sheet. Toss the kale with the remaining 1 tablespoon oil and a pinch of salt. Arrange in a single layer in the middle of the foil. Nestle the fish fillets on the kale and sprinkle with 1/4 teaspoon of salt. Evenly spread the green curry sauce over each filet. Top loosely with another 24-inch piece of foil (try to keep the foil from touching the fish) and seal the edges.
Bake the foil pack until the fish is just cooked through and the greens are crisp-tender, 15 to 20 minutes. Carefully unseal the foil pack, and divide the fish and greens among four plates. Top with cilantro and serve with lime wedges.