To prepare filling: Combine the strawberries, rhubarb, ½ cup sugar, cornstarch or tapioca, 1/8 teaspoon each cinnamon, ginger, and nutmeg, in a 9 inch deep dish pie plate. Let it stand for at least 20 minutes.
Preheat the oven to 400 degrees.
To prepare the topping: Stir together the flour, sugar, salt and spices listed above for the topping. Cut in the butter with two forks or your fingers until crumbly. Stir in the buttermilk just until combined. (The buttermilk is the “acid” needed to activate the baking soda)
Using a large spoon, drop the dough in 8 big dollops over the filling and sprinkle with the remaining 1 tablespoon sugar. Bake until browned and bubbling, 40-50 minutes. (It’s wise to have a pan or tray under this cobbler as the juices tend to get exuberant) You can cover it with foil if it’s browning too quickly. Serve this warm. It’s a real treat.