In a large bowl, or the bowl of a stand mixer fitted with a dough hook, mix together the flour, yeast, salt and sugar.
Add the beer or water, lukewarm milk and melted vegan butter and mix to form a rough dough. Knead the dough for about 10 minutes until it is smooth and elastic. It should feel quite soft and tacky to the touch but not overly sticky. If it is too wet then knead in a little more flour as needed.
Place the dough in a large, lightly oiled bowl, cover and set aside to rise until it is doubled in size, about 1 ½ hours at warm room temperature, or overnight in the fridge.
Punch down the risen dough and give it a very brief knead to knock out the air then divide it into eight even pieces, I use a scale for accuracy. Shape each piece into a ball.
Roll one of the pieces of dough out into a rough square shape. If the dough is sticking you can lightly flour the worksurface and rolling pin.
Roll the dough up tightly from one edge into a sausage. Roll over the sausage with your hands to form a rope about 35 cm (14 in) long.
Use a sharp knife to cut the rope into 8 pieces. Place them spaced apart on an oiled board and repeat with the rest of the pieces of dough.
Leave the bites uncovered to rise for about 20-30 minutes, until they are puffy.
Meanwhile preheat the oven to 220°C/200°C fan/425°F/gas mark 7. Line a couple of baking sheets with baking parchment.
When the bites have nearly finished rising, heat the 2 litres of water in a large pan until it comes to the boil then turn down the heat so that it is not even simmering and stir in the 5 Tbsp of bicarbonate of soda (baking soda).
Working in about 4 batches, drop the bites into the water and leave for 30 seconds. Use a timer!
Use a large slotted spoon to remove the bites from the bath and place them spaced apart on the lined baking trays. Sprinkle the tops of the bites with a bit of pretzel salt or flaky sea salt. Repeat with the rest of the bites.
Bake the pretzel bites for 8-10 minutes until they are deep brown.
When the pretzel bites come out of the oven, brush them generously with melted vegan butter then transfer them to a wire rack to cool a little before serving.