Heat the oven to 375°F with a rack in the middle position. In a small saucepan, combine the butter, coconut oil, sugar and 3 tablespoons water. Bring to a simmer over medium-high, stirring to melt the solids. As soon as they’re melted and the mixture is simmering, add the flour and salt. Remove the pan from the heat and, working quickly, stir with a silicone spatula until the dry ingredients are evenly moistened and without any dry patches; the dough will be very soft and resemble mashed potatoes.

Scrape the hot dough into the center of a standard 9-inch pie plate. Using the spatula or the bottom of a dry measuring cup, press the dough into an even layer into the bottom of the pie plate. When the dough is cool enough to handle, use your hands to continue to press it into the corners and up the sides of the pie plate until the dough lining the sides is of even thickness and stands about ½ inch above the rim. Flute or crimp the edge, making sure it sits on the rim of the pie plate; this will help prevent the sides from slipping during baking.

Carefully line the dough with a large sheet of foil, gently pressing it into the corners and against the sides, then fill with about 2 cups pie weights. Bake until the dough is set, about 20 minutes. Carefully lift out the foil with weights, then prick the pie shell all over with a fork to deflate any air bubbles and prevent additional ones from forming. For a partially baked pie shell, bake until lightly browned, another 10 to 12 minutes; for a fully baked pie shell, bake until deep golden brown, another 15 to 17 minutes. Transfer to a wire rack and let cool.