Place raisins in a bowl with vanilla, cover with hot water, and let soak 10–15 minutes. Strain and towel dry.
Cream butter, turbinado sugar, and brown sugar until light and fluffy.
Add egg, vanilla, and active starter; mix until smooth.
In a separate bowl, combine flour, oats, baking soda, salt, and cinnamon. Add to wet ingredients and mix just until combined.
Gently fold in raisins.
Scoop dough into ~75g portions, roll into balls, and flatten slightly.
Freeze 30 minutes, then refrigerate for 2 hours.
Bake at 350°F for 15–18 minutes, until edges are set and centers stay soft.
Cool on the tray for 10 minutes, then transfer to a rack.
