You've just got your first jar of sourdough starter, how exciting! Once you've tasted homemade bread, you'll never buy storebought again. As someone who suffered from cramping and bloating from "regular" bread, sourdough was like a gift from the heavens. It wasn't all smooth sailing though. My first couple of loaves were flat and dense, not big and fluffy like the ones I'd seen online. I had to search YouTube and Google for the answers, and everyone said something different. I'd waste time and flour, but in the end, I learned how to bake delicious sourdough loaves. I'm by no means an expert, but I can tell you what I've learned and how to get started.
1) Feed your starter
Your new jar of starter is a microbial culture. Essentially, it's alive! That means it needs feeding to stay healthy and active, at least once every two days (if you don't want to feed it that often, pop it in the fridge for up to two weeks and feed once you take it out again), with an equal measurement of starter, water, and flour. I feed mine 1:1:1, and always by weight. For example, I weigh 100g of starter, 100g of water, and 100g of flour in a bowl. I mix it and pour back into my glass jar. I put an elastic band around the jar at the level of the mixture, so I can see how much it rises. You want it to rise at least 50% before baking with it.
People often stress out about feeding, but it's easy once you've done it a few times and tracked the starter's progress. Let your eyes and nose be the judge. If you fed your starter hours ago and it looks flat and doesn't have a lot of bubbles, it's likely that you missed the peak and it sunk back again after eating through all its food. Or it may be a cold day and it's just eating more slowly. Alternatively, you could have taken it out of the fridge and it's sluggish (feed your starter twice after coming out from the fridge, so it comes back nice and bubbly). There are so many factors that affect the speed of your starter, and you'll notice it changes depending on season and where it's placed in your house. The smell also helps you judge how the starter is going. If it's sour, it's hungry. If it smells delicious (mine smells a little like bananas), it's ready! The best way to learn is by doing and watching, so don't be afraid to waste a bit of flour and time. Your starter won't die if you feed it every 1-2 days or if you leave it in the fridge for a couple of weeks. If you're worried about accidentally killing it, leave a portion in your fridge as a backup and the main jar on your counter.
2) Mix everything together
Now that your starter has doubled, it's ready to mix with your flour, salt, and water. But if you're not sure it's done, drop a teaspoon of starter in water. If it floats, it's good to go. If not, leave it for a little longer. Remember, whatever your starter looks like, your bread will too, so use that as a rule of thumb.
Now that your starter is ready, you'll need a sourdough recipe. If you don't have one, try this everyday sourdough loaf. I use it daily and absolutely love it! Come back here once you've mixed your flour and water, and completed autolyse (period of rest).
Okay, now you've mixed everything, it's time for the stretch and folds. This helps strengthen the gluten in the bread and is the part of the process where you can control the structure of the bread. Here is a video that demonstrates it well.
You'll notice that sourdough requires a lot of waiting. Keeping a timer on all the time is a part of my sourdough routine, and often I keep a tally of how many stretch and folds I've done so I don't under or overdo it.