Grilled Red Onion and Cucumber Salad with Yogurt Mint Dressing

Name: Grilled Red Onion and Cucumber Salad with Yogurt-Mint Dressing
Ingredients: 1 cup plain yogurt, drained in fine sieve about 30 minutes; 1/4 cup chiffonade fresh mint; 2 tablespoons fresh lemon juice; 2 tablespoons tahini; 1 tablespoon olive oil; 1/4 teaspoon cumin; 2 cloves garlic, finely chopped; Kosher salt and freshly ground black pepper; 2 red onions, peeled and sliced 1/2-inch thick crosswise; Olive oil, for brushing; 3 tablespoons finely chopped fresh oregano; 3 cucumbers, peeled, halved lengthwise and sliced 1/2-inch thick; 1/2 cup crumbled feta