The Old Redwood Barn at Gundlach Bundschu Winery in Sonoma. SONOMA — Sixth-generation winemaker Jeff Bundschu is the one-of-a-kind personality who runs one of Northern California’s oldest and most historic winery’s: Sonoma’s Gundlach Bundschu. He joins Coco Sterzenbach and Mike DeWald on this week’s episode of the Rock’N Vino podcast.…