Whole-Wheat Feta Tart with Caramelized Onions and Herbs

Ingredients

• Whole-Wheat Crust
• 1 cup (120g) all-purpose flour
• ⅔ cup (75g) whole-wheat flour
• 2 tablespoons granulated sugar
• ½ teaspoon fine sea salt
• ½ cup (120g) extra-virgin olive oil
• 2 to 4 tablespoons milk
• Feta Filling
• 2 tablespoons unsalted butter
• 2 large red onions—peeled, halved and thinly sliced
• Kosher salt and freshly ground black pepper
• 2 tablespoons red wine vinegar
• 8 ounces (226g) cream cheese, at room temperature
• 12 ounces (340g) feta, cubed
• 2 tablespoons extra-virgin olive oil
• 3 tablespoons chopped fresh parsley
• 2 tablespoons chopped fresh dill
• 2 tablespoons chopped fresh mint
• 2 tablespoons chopped fresh oregano
• Red-pepper flakes, to taste