|A present of a little of your established starter really can be the present that keeps on giving|
My starter came from my friend Emily; about three years ago now. Her starter was already going on for 18 months old itself, if I recall correctly.
Since I got that fantastic, promising present, my own starter has gone on to spawn many other sourdough starters, not least that of John-Paul Flintoff.
Anyway. I've been meaning to, for ages, write up here about What To Do when someone gives you some starter, so here I go.
You could of course give someone a full jar of starter ready to go since, if you have some levain on the go, it wouldn't take long at all for you to build it up to a whole other working jar size. But this isn't madly practical unless you can actually hand it over in person. And, also people like to build it up themselves. So what I do when I'm sharing starter is send it on the dry side, so it's less frisky and likely to tire itself out. I either send it in a small plastic lidded box or double bag it in those sealable sandwich bags.
Hopefully, before you are sent a starter of starter, you will have ready:
A large jar
Some white, strong bread flour.
Weigh the jar when it's empty and make a note of it.
What you do when you get it is this:
Put the starter in your jar. Add 50g white strong bread flour, and 40g of out of the tap water. Mix it up well and put the jar aside. In the fridge or a cool place in your kitchen.
You don't need to remove any starter, you do that when your starter is big and to keep refreshing it would mean you'd end up with unfathomable amounts of the stuff.
The next day, if you want to, take out a tablespoon of starter and discard it. There is no reason for this, it just kinda feels authentic. Add another 50g white strong bread flour and 40g of water.
What you want to do is build up so that you have about 300g of starter in your jar (because for most breads you use about 200g of starter). So you keep repeating this until your jar is about 3/4 full when it's just refreshed.
Never fill it up to the top as if you do, as the starter grows (because it will go up and down during the day until it settles) the jar can explode. Don't worry if you look at your starter during the day and it regularly goes up to near the top, that's normal. What it mustn't ever be is that full when it's just ben refreshed.
When you've got about 300g of starter going (this is why you weigh the jar empty) you're ready to go. Every time you bake - presuming you use 200g of starter, refresh your jar with 120g of white bread flour and 100g of water. Or, if it's looking a bit full already, 100g of flour and 80g of water.
And you're ready for a life time of baking.
Unless you bake every day, keep your starter in the fridge. I bake bread about 2/3 times a week and never need to discard starter to refresh it, I just use it straight from the jar.
I hope this makes sense, do ask any Qs if you need to (on here please so others can benefit).