Chicken Stroganoff

Ingredients

For 4 servings

• 1 pound boneless skinless chicken breast (2 pieces)
• 2 tablespoons olive oil
• 1 teaspoon kosher salt (divided)
• ½ teaspoon black pepper (divided)
• 1 tablespoon unsalted butter
• 1 cup diced yellow onion (¼" dice)
• 1 tablespoon minced garlic
• 8 ounces brown mushrooms (½" thick slices)
• 2 tablespoons all-purpose flour
• 1 ½ cups unsalted chicken stock (or broth)
• 1 tablespoon Dijon mustard
• ½ cup sour cream
• 2 teaspoons chopped parsley