In a large mixing bowl, whisk together flour, baking powder, salt, and sugar until well combined.

In a separate bowl, mix sour cream, blood orange zest, and juice, then fold into dry mixture until just combined.

Cover dough with plastic wrap and refrigerate for about 1 hour.

Lightly flour a surface, roll out dough, and cut into doughnut shapes.

Heat oil in a deep skillet to 375°F (190°C) and fry doughnuts for 2-3 minutes on each side.

For the glaze, whisk powdered sugar and blood orange juice until smooth, then dip warm doughnuts.

Sprinkle with poppy seeds while the glaze is wet and set on a wire rack.

Serve warm with your favorite beverage.