Add the water, milk and sourdough starter to a mixing bowl and stir until the sourdough starter is dissolved (it's ok if there's still a few chunks).
Now add the bread flour, melted butter and salt to the liquid and bring together to form a shaggy dough. Cover and leave to sit for around an hour.
Tip the dough out onto a clean surface and knead it until the dough is soft and supple. You can do this step in a stand mixer or Thermomix if you prefer. It will take around 10 minutes to knead by hand and around 5 minutes in a stand mixer.
Place the kneaded dough back into a bowl and cover. Allow it to rise around 50%.
While the dough is rising, make the filling for the dough so that it is ready to go when you need it. Simple chop all the herbs and garlic really finely (so that it's like minced herbs) and then add the herbs and parmesan cheese to the butter. Mix until well combined. You can do this in a food processor if you prefer. Set aside. Once the dough has risen a bit, tip it out onto a clean surface and gently shape it into a rectangle with the long edge in front of you. You're looking for a rectangle of around 25" x 8" (64 x 20 cm). Don't be afraid of degassing the dough as it will puff up in the next stage.
Now spread the herb and garlic filling all over the dough, leaving a 1" strip at the top with no filling.
Roll the dough up into a big log - just like you would if you were making cinnamon rolls. Make sure it's rolled fairly tightly. Seal the dough up along the seam and roll it over so that the seam is at the bottom.
Using a knife or dough scraper, cut the log through the middle all the way up, leaving just a small part of the dough attached so you have two strands. You will be able to see the swirls of garlic and herb butter where you have sliced it (refer to step by step photos in the blog above for visual aids on how to do this).
Now, twist the two strands of dough together to form a "rope". Gently push the ends together so that both ends of the rope are sealed. My rope was around 30" (76 cm) long when I finished (the dough does stretch a bit).
Now form the rope into a letter "S" curling each end in towards the middle. This forms your twist. You can see how I've done this in the photos further up the page.
Place your sourdough herb and garlic twist onto a baking tray lined with parchment paper, cover with a damp dishtowel and allow to proof for a few hours. You want your dough to be nice a puffy before you bake it.
Once the dough has proofed, preheat the oven to 200C (392F) and bake for around 40 minutes or until golden. I recommend placing your twist on the lower shelf to avoid it burning. If your oven is fan forced or it runs hot, reduce this to temp to 180C (356F).
When the twist is cooked, remove it from the oven. Be careful if your baking tray has no sides as some of the butter may drip over the sides.
Brush the finished bake with excess butter and serve warm.