First, line a sheet pan with parchment or wax paper and slide it into the freezer to chill while you work. A cold tray sets the first side almost on contact.

Next, whisk the Greek yogurt, powdered sugar, vanilla and salt together until completely smooth. Drag a ribbon of glaze across the surface with the whisk. It should hold its shape for about 3 seconds before sinking back, and if it disappears at once, add more powdered sugar a quarter cup at a time.

Then drop a pretzel into the bowl, turn it once with a fork, and lift it out flat on the tines. Tap the fork against the rim six or seven times to shed the excess rather than scraping it, which strips the coating out of the loops.

After that, set each one on the chilled tray with a little space around it and scatter sanding sugar over while the surface is still wet. Work in batches of eight or ten, because the glaze stiffens as it stands.

Finally, freeze the tray flat for at least 2 hours. A pretzel is set when the top feels firm and slightly waxy and leaves nothing on your fingertip.

Drizzle melted chocolate over half of them, return the tray to the freezer for 10 minutes to fix it, then transfer everything to a sealed container. Serve straight from the freezer.