Pre-heat the oven to 425°F.
Melt butter in a 9-inch or 10-inch cast iron skillet.
From the lemon, finely grate 2 teaspoons zest into the melted butter; set aside.
Into a medium bowl, squeeze 1 tablespoon lemon juice; add strawberries, ¼ cup granulated sugar and ¼ teaspoon salt; toss until the sugar has started to become syrupy, coating the berries; using a hand to toss here helps the sugar melt faster; set aside.
In a separate medium bowl, whisk together the flour, baking powder, remaining ½ cup granulated sugar and ½ teaspoon salt.
Mix the milk into the melted butter.
Slowly pour the milk mixture into the dry ingredients while stirring with a spatula or spoon until just combined; the batter will be thick but spreadable.
Transfer batter to the buttered skillet and spread in an even layer.
Arrange the strawberries in the batter, cut sides down, pressing them slightly.
Pour their syrup over the top; carefully pour the boiling water over the top.
Place in the pre-heated oven, on the middle rack, and bake until the cake is golden brown and a warm, pudding-like sauce has formed below the strawberries; 25 to 27 minutes.
Remove from the oven and dust with confectioners’ sugar or serve with sweetened whipped cream, if desired.
Serve warm; as the pudding cake sits, the pudding will eventually soak into the cake, so is best enjoyed sooner rather than later.
To re-heat, pre-heat the oven to 300°F; place in the pre-heated oven, uncovered, and bake for 10 to 15 minutes.
