Preparation

• Peel and cut potatoes into 1/4-inch thick slices.
• Transfer potato slices to a bowl of cold water as you work.
• Melt 3 tablespoons of the butter in well-seasoned 9-inch or 10-inch cast iron skillet over moderate heat, turning to coat the surface.
• Remove skillet from heat.
• Dry the potatoes very well, then arrange half of them in an overlapping pattern in the skillet, making sure the bottom is completely covered.
• Press down firmly all over with a spatula, then season with salt and pepper.
• Arrange smoked salmon, goat cheese, garlic and onions on top of the potato layer.
• Top with remaining potatoes and press down.
• Dot the top with the remaining 1 tablespoon butter and season with salt and pepper.
• Cover and cook over low heat until the bottom of the galette is crisp and the potatoes are tender, about 45 minutes.
• Carefully loosen the galette with a spatula, invert onto a plate and slice into triangles.
• Garnish with green onions and serve.
• Serves 4.