Strip Steak with Lemony Yogurt and Radishes

Name: Strip Steak with Lemony Yogurt and Radishes
Ingredients: 2 (1-inch-thick) boneless New York strip steaks (about 10 ounces each); 2 tablespoons olive oil, plus more for drizzling; Kosher salt; 3 tablespoons unsalted butter; 4 sprigs thyme; 2 garlic cloves, crushed; 6 cardamom pods, lightly crushed; 1 1/2 teaspoons finely grated lemon zest; 1 teaspoon plus 1 tablespoon fresh lemon juice; 1 1/2 cups plain whole-milk Greek yogurt; 8 ounces radishes (such as red radishes and/or daikon), some cut into wedges and some sliced; 1 cup (packed) parsley leaves with tender stems; Crushed red pepper flakes and flaky sea salt (for serving)