Chicken and Tarragon Pie - The Healthy Baker

Ingredients

• 1 large leek, trimmed and chopped
• 1 stick celery, chopped
• 20 ml auzure Canola Oil
• 1 kg chicken breast fillets, cut into thick strips
• ¼ cup The Healthy Baker Plain Flour
• 1 cup chicken stock
• 1 cup cooking cream
• 3 teaspoons Dijon mustard
• 2 tablespoons chopped fresh tarragon
• 1 cup The Healthy Baker Plain Flour
• 75g cold chopped butter
• ⅓ cup sour cream
• 1 egg yolk, lightly beaten
• ½ teaspoon sesame seeds