Ingredients

• 3 tablespoons grapeseed or avocado oil, divided
• 1 pound boneless, skinless chicken thighs, trimmed
• ¾ teaspoon salt, divided
• ½ teaspoon ground pepper, divided
• 12 ounces mixed mushrooms, coarsely chopped
• 2 cups sliced leek (1 medium), rinsed well
• 2 cloves garlic, minced
• 2 teaspoons chopped fresh thyme or tarragon, plus more for garnish
• 3 tablespoons all-purpose flour
• 3 cups low-sodium chicken broth
• 2 cups frozen peas
• 1 tablespoon dijon mustard