Margaret Fox's Amazon Chocolate Cake

INGREDIENTS

• 1 1/2 cup all-purpose flour
• 1 cup sugar
• 1/3 cup unsweetened cocoa
• Confectioners' sugar (optional, for dusting)
• 1 1/2 teaspoon vanilla
• 1/2 teaspoon salt
• 1 teaspoon baking soda
• 5 tablespoons neutral oil (like corn, canola, or vegetable)
• 1 cup cold water
• 1 tablespoon cider or white vinegar