Method

1. In a bowl whisk the egg yolks vinegar, mustard powder, salt and pepper. Once combined slowly add the Borderfieldsand continue to mix until all the Borderfields has been incorporated and it reaches a thick, mayonnaise-like consistency. Add the lemon zest and tarragon leaves.
2. Pre-heat a deep fat fryer to 170°C, or a pan half filled with vegetable oil if you don’t have a fryer.
3. Place the flour and garlic powder in one bowl, eggs and milk in a second, and panko breadcrumbs in a third.
4. Roll the mushrooms in the flour, dip into the beaten egg mixture, and finally coat in the panko breadcrumbs. Repeat until all the mushrooms are coated.
5. Carefully lower the mushrooms into the oil and fry for 3-4 minutes or until golden all over and cooked through. Serve the mushrooms with the mayonnaise.