Creamy Roasted Red Pepper Soup with Tahini and Feta

Name: Creamy Roasted Red Pepper Soup with Tahini and Feta
Prep time: 20 min
Cook time: 33 min
Total time: 53 min
Cuisine: European, Mediterranean, Middle Eastern
Ingredients: 1 medium yellow onion; 3 cloves garlic; 1 (16-ounce) jar roasted red peppers; 1 medium lemon; 2 tablespoons olive oil; 2 tablespoons double-concentrated tomato paste, from a tube; 1 (32-ounce) carton low-sodium vegetable or chicken broth; 1 1/4 teaspoons kosher salt, divided, plus more as needed; 1/4 teaspoon freshly ground black pepper, plus more as needed; 3 tablespoons well-stirred tahini, divided; 2 ounces feta cheese; 3 sprigs fresh oregano or thyme, for serving (optional); 1 teaspoon za’atar seasoning, plus more for serving