Preheat oven to 350º.
Put 2 Tbsp. butter in a round, and place in the oven until it melts. Using a hot pad, tilt pan to coat bottom and sides with butter. Set aside until after cake batter is made.
In a bowl, combine flour, baking powder, soda, salt and cardamom (if you using it).
In a Kitchenaid or similar mixer, cream butter and brown sugar on medium speed for 3 minutes, scraping occasionally. Add egg and vanilla and beat another minute.
Add dry ingredients and turn mixer on low. Then add in sour cream, and mix until just combined.
Sprinkle the cake pan with the reserved 1/4 cup brown sugar. Place strawberry slices over the brown sugar, covering the entire bottom.
Spoon the batter over the strawberries, and spread out until it covers evenly.
Bake for 35 minutes, or until a toothpick inserted in the center comes out clean.
Cool for a few minutes. Then place a large plate or platter over the cake pan, and using potholders, flip the entire thing over, so the cake comes out of the pan onto the plate upside-down.