Warm the oat milk, stir in sugar and yeast. Let it bloom 5–10 minutes until foamy.
In your KitchenAid with the paddle attachment (not the dough hook, GF dough is more like a thick batter), combine the flour, psyllium husk, baking powder, and salt.
Add the yeast mixture, melted butter, egg, and vinegar. Mix on medium for 2–3 minutes. It'll be sticky and thick, more like muffin batter than traditional dough. That's correct, don't panic.
Line a baking sheet with parchment. Using wet hands or an ice cream scoop, portion into 6 rounds. With wet fingers, flatten each round to about 4 inches wide and ¾ inch tall. They won't spread much on their own, so what you shape is what you get.
Cover loosely with plastic wrap and let rise in a warm spot for 45–60 minutes. They won't double like wheat dough, but should puff noticeably.
Brush tops with egg wash or oat milk, sprinkle with sesame seeds or cornmeal for the classic bun look.
Bake at 375°F for 18–22 minutes until golden and they sound hollow when tapped. Check at 18 min, GF bread dries out fast if overbaked.