Strike grains with 5.05 gal of water at 171.4 °F.
Mash at 160 °F for 60 min.
Vorlauf and lauter 3.34 gal in your first runnings.
Add 3.66 gal of sparge water at 168 °F.
Vorlauf and lauter 3.66 gal in your second runnings.
Your combined runnings should be 7 gal.
1.5 qt / lb 60 mins mash
ferment 68/70 2 weeks
then secondary
a very high mash temp is recommended (158°F-160°F) i
"I've actually had some really good experiences with the roselaare blend. My first beer was good to go after 1 year. I did something wierd though. After abcouple months I tranferred to a secondary, and a few months later repitched a jar of the culture that I poured off the primary. I don't know why I did that, but it seems to kick the souring into a higher gear. I've reused it a couple times, and it seems to be souring just fine."
https://byo.com/article/flanders-red-ale/