In a mixing bowl combine the flour, cut up butter, sugar, baking powder, sea salt, and milk. Use an electric mixer with the beaters attached to blend until the mixture resembles coarse dough crumbs.
Flour a clean work surface. Turn the dough crumbles out onto the surface. Bring the dough together using your hands to form a ball. Press the dough flat to between 1/4 and 1/3 inch thick.
Use a 2-inch cookie cutter to cut out circles of dough. Bring remaining dough together and press out again, repeating until all the dough is used.
Heat 1/2 inch canola oil in a deep frying pan to 350 degrees F. Use a slotted heat-proof spoon to lower the dough circles into the hot oil, working in batches to avoid overcrowding the pan. Fry for about 2 minutes, or until golden brown, reducing the heat if needed to prevent burning. Remove with the slotted spoon to paper towels to drain.
Pour the sugar out onto a plate. Roll each donut in the sugar while still hot. Serve warm.