In a 12-inch cast-iron skillet, add flour; slowly whisk in cream until smooth. Whisk in garlic, parsley, oregano, thyme, zest, ¼ teaspoon salt, and pepper. Bring mixture to a low boil over medium heat, whisking frequently; cook, whisking constantly, until thickened and bubbly, about 4 minutes. Pour sauce into a small bowl; keep warm. Wipe skillet clean.
In skillet, heat oil over medium-high heat. Add asparagus and remaining ½ teaspoon salt; cook, turning occasionally, until browned, about 10 minutes. Drizzle warm sauce onto asparagus. Garnish with lemon zest, if desired. Serve immediately.
Notes
Green beans can be used instead of asparagus.
Recipe by Southern Cast Iron at https://southerncastiron.com/blistered-asparagus-herbed-cream-sauce/