Noob question

So I have never done a sour beer but am going to try my first oud bruin in the next week or two. Quick question. I see a lot of recipes and suggestions to use a cal ale yeast or something, under pitch it then transfer to secondary and pitch the bugs and let ride for months. Does it need to be taken off the original yeast bed? Could I just under pitch, let it ride for 6-10 days then pitch in the rosalare and additional bottle dregs of whatever and let it all sit for months? Or, will i get bad flavors from the original yeast just chilling for months and months and months?
I was thinking of doing a 10g batch. splitting it up and doing both with rosalare, and adding dregs of supplication and maybe cantillion or something to one but not to the other to see how they differ.

Thanks so much, appreciate the help and assistance!

Sure, you could let it all ride with no secondary. Technically it wouldn't be an Oud Bruin as they are traditionally out in secondary. But, it's you beer so who cares

As for off flavors, it's possible that you could get some early on but the longer it sits, it should clean up and develop some awesomeness.

I have a sour going on 15 months that was just this. Pitched American ale yeast and a few days later tossed in a pack of Rosalare. At about a year, it was cry baby sour. At around 14 months, it's mellowed and tastes nice.

Thanks for the reply!

If I transferred to a secondary 6.5 gallon glass carboy and pitched bugs, would there be too much headspace in there or would it be fine still?

dont bother with the cali yeast, just go with roe right away if you plan on using it. its got sacch in it so no point in using another strain first, plus its much slower adding it in secondary

i wouldnt leave that much headspace, but a pellcile will form and limit oxygen exposure so you'd probably be OK

Will the rosalare create a large or even any real Krausen? I have a 5g glass fermenter also but figured that would be too little room.
And I thought usually the oud bruin style calls for the original some sort of sacch yeast and then secondary in barrel or oak with bugs.

the roe ferment will look like any normal ferment, a 5G fermenter for 5G will definitely not work

right, that is the traditional way, but the barrels have heartier bugs & the benefit of oxygen exposure that a fermenter won't have. you can certainly do it that way, but its slower and doesn't typically get as sour at home.