Preheat oven to 200 degrees C and grease a 23cm round cake tin. Dust the tin with 1 tablespoon cocoa.
In a large bowl, whisk together the flour, 1/3 cup cocoa, bicarb soda, sugar and salt. In a separate bowl or glass jug, stir together the coffee, oil, vanilla and vinegar, then whisk into the dry ingredients until just blended.
Pour into prepared cake tin and bake until it tests done, about 25 minutes.
Let cake cool in the tin then turn out on a serving plate. Serve with whipped cream.