INSTRUCTIONS

1. Stir vinegar, buttermilk, and water in a small bowl; set aside. In the bowl of a food processor, pulse together flours and salt. Add butter, pulsing until reduced to a fine crumb. With motor running, slowly stream in buttermilk-mixture (don’t worry if it seems like a lot) until dough starts to form a ball and pull away from the sides (this dough is very sticky and wet). Wrap dough in plastic wrap, flatten, and refrigerate for 1 hour.
2. Meanwhile, heat a large pan over medium-high. Once hot, add oil then mushrooms. Cook, stirring occasionally, until golden-brown and shrunk to half their size, about 6 to 8 minutes. Transfer to a bowl.
3. Reduce heat to medium then add butter. Once melted, add shallots, garlic, and thyme sprigs. Cook, until shallots start to soften, and mixture is fragrant, about 2 to 4 minutes. Add reserved mushrooms then increase heat to medium-high. Add wine and cook until almost reduced; stir in cream and salt. Bring to a simmer then reduce heat to medium-low. Cook until slightly thickened, approximately 3 to 4 minutes. Remove from heat and discard thyme sprigs. Set aside to cool completely.
4. Preheat oven to 425°F.
5. Once dough has rested and filling has cooled, place dough on a large piece of parchment. Roll into a rough 12-inch circle. Transfer parchment and dough to a large baking sheet. Spread filling over dough leaving a 1-inch border. Then fold over edges to create a rustic tart.
6. Bake, in center of oven, until dough is golden-brown, about 30 to 40 minutes.
7. Serve warm with a fresh green salad on the side.