In a bowl, combine 1/4 cup of the warm water with the baking powder. In a food processor, combine the semolina with the flour, yeast, sugar and the remaining 2 3/4 cups of warm water; process for 30 seconds, until smooth. Add the salt and baking powder mixture and process for 30 seconds longer. Pour the batter into a large bowl, cover with a kitchen towel and let rise at room temperature until doubled in bulk, about 1 hour.
Heat a 10-inch nonstick skillet and coat it with a thin layer of vegetable oil. In a small bowl, blend the honey with the melted butter. Whisk the batter until creamy. Ladle 1/3 cup of the batter into the skillet, tilting the skillet to distribute it evenly. Cook the pancake over moderate heat until bubbles appear all over the surface and the bottom is pale golden, about 2 minutes. Shake the skillet to loosen the pancake, then slide the pancake onto a plate. Drizzle with the honey butter and serve right away. Repeat with more oil and the remaining batter and honey butter.
Notes Fine semolina flour, sometimes also called extra-fancy durum flour, is available at Whole Foods and online at kingarthurflour.com.