In a large mixing bowl, combine the plain flour, baking powder, and salt. Mix well.
Add the softened butter and rub it into the dry ingredients until the mixture resembles breadcrumbs.
Gradually add the warm water, mixing until a soft dough forms. Knead the dough for about 5 minutes until smooth.
Cover the dough with a damp cloth and let it rest for 30 minutes.
Once rested, roll out the dough on a lightly floured surface to about 3 mm thickness. Cut into small squares or triangles, about 5 cm wide.
Heat the sunflower oil in a deep pan to 190°C. To test, drop a small piece of dough into the oil; it should sizzle and float to the surface.
Fry the sopapilla pieces in batches, turning occasionally, until golden and puffed up (about 1–2 minutes per batch). Remove and drain on kitchen paper.
Mix the caster sugar and ground cinnamon in a small bowl. While the sopapillas are still warm, sprinkle with the cinnamon sugar.
Drizzle the sopapillas with honey and serve immediately.
