Roasted Root Vegetable Salad with Mint and Pistachios

Name: Roasted Root Vegetable Salad with Mint and Pistachios
Ingredients: ½ cup unsalted, shelled raw pistachios; 1 small or ½ large acorn squash, halved through root end, seeded, sliced crosswise ½” thick; 4 small carrots, peeled, cut into 2” pieces; 2 medium parsnips, peeled, sliced ¾”-thick; 1 medium golden beet, peeled, halved, sliced ½” thick; 5 tablespoons olive oil, divided; Kosher salt and freshly ground black pepper; 2 tablespoons (or more) apple cider vinegar; 1 teaspoon sumac (optional); 1 cup fresh mint leaves, torn if large