In a large bowl, whisk together the flour, semolina, sugar, yeast, and salt.

Pour in the warm water and whisk until the batter is smooth and lump-free, about as thick as heavy cream. Stir in the orange zest if using.

Cover the bowl with a towel and let the batter rest at room temperature for 45 minutes, until it looks puffy with small bubbles on top.

Pour the olive oil into a 25 cm / 10-inch nonstick skillet and heat over medium heat to about 350 F / 175 C. Test the oil with a small drop of batter, it should sizzle and float right away.

Ladle about 60 ml / 1/4 cup of batter into the oil for each pancake. Fry only 2 at a time so they have room to spread and crisp evenly.

Cook for 2 to 3 minutes per side, until deep golden brown and crisp at the edges. If the outside browns before the middle looks set, lower the heat slightly for the next batch.

Lift the pancakes out with a slotted spatula and drain on a paper-towel-lined plate. Repeat with the remaining batter, adding a little more oil to the pan if it runs low.

In a small bowl, mix the sugar and cinnamon for the topping.

While the pancakes are still warm, dust them generously with the cinnamon sugar on both sides.

Serve right away, while the edges are still crisp.