Cube Steak with Mushroom Gravy

Name: Cube Steak with Mushroom Gravy
Ingredients: 1 large yellow onion; 8 ounces baby bella or cremini mushrooms; 1 sprig fresh parsley; 3/4 teaspoon kosher salt, plus more as needed; 1/2 teaspoon garlic powder; 1/4 teaspoon freshly ground black pepper, plus more as needed; 1/4 cup plus 2 tablespoons all-purpose flour, divided; 4 cube steaks (about 1 pound total); 2 tablespoons olive oil, divided; 3 tablespoons unsalted butter; 1 cup water; 1 cup low-sodium beef broth; 1 (1-ounce) packet onion soup mix