All you'll need to make your sourdough starter is strong white flour and water.
Day 1. Gently mix 10g Marriage's Finest Strong White flour & 10ml warm water into a paste. Then put the paste in a plastic tub with the lid ajar or covered in muslin cloth (so that the air can ferment the paste) and keep it at room temperature.
Day 2-5. Each day add an additional 10g flour & 10ml warm water each day and gently mix until you have a total of 100g of sourdough starter.
At this point the mixture should start to bubble and have a bit of body. It should also have a healthy sour smell.
Day 6. Add 100ml of water and 100g of flour to your 100g of sourdough starter and mix gently (at this point your total will be 300g).
Day 7-13 To start feeding your sourdough starter remove 200g and replace with 100g of Marriage's Finest Strong White flour plus 100ml cold water (to bring the mixture back to 300g). Mix well until it’s a smooth consistency - do this every day until day 14. After day 7 the sourdough starter is best kept in the fridge.
Day 14. The 200g that is removed on this day should be strong enough to use as your sourdough starter. Add 100g flour and 100ml water to the remainder of the sourdough starter (so that you bring the mixture back to 300g) - this can be kept in the fridge and fed with more flour and water to use in future batches.