Heat oven to 400° F. Coat both sides of all the fish with 2 tablespoons of the oil and place in a single layer in a roasting pan. Season with 1 teaspoon of the salt and a few grinds of pepper. Cut the lemons crosswise into 10 slices and place on top of the fish. Roast until the fish is just cooked through, about 15 minutes. Meanwhile, in a large skillet, melt 2 tablespoons of the butter over medium heat. Add the walnuts. Stir occasionally until lightly browned, 3 minutes. Remove from skillet and set aside in a bowl. Add the remaining oil and butter and the garlic to the skillet; cook for 30 seconds. Add the kale, 1/2 cup water, and the remaining salt. Toss, cover, and cook until wilted, 5 minutes. Add the walnuts. Serve 4 fillets with the kale and the Roasted Acorn Squash. Reserve 4 fillets for Halibut Wrapped in Grape Leaves; freeze the other 2.