It is really easy. 100ml (gms) of water 100gms of plain white hard bread flour say 3 gms of instant dried yeast, mix with a fork in the bowl you'll use for mixing with a shower cap on it. Leave overnight.

This is for loaves not baguettes and is for 600gms (200 gms of poolish + second day ) 250gms of flour + 150 gms of water of finished dough ie two very small loaves with lots of crust.

The following day you will want it to end up with say 70% hydration.
So to the above mix add 250gms or so of flour (my favourite is a blend 180gms of white and 35 gms each of wholemeal and rye. Add 140 ml of water perhaps another gm or two of yeast o one side and say 6 gms of salt on the other. Mix it for say 5 minutes, let it rise, once risen envelope folds.

If you make a steam oven as I mentioned earlier and pictured again below - you'll have a couple of small crusty loaves with a real sheen. And when you buy a baguette tin I teach you to make baguettes better than 99% 0f those you've ever eaten.



If you add some onion/nigella seed it will look like this and look at the open sour-dough looking texture on the second loaf. This is a poolish started loaf and not sourdough.




A proper cheats steam oven.